Battle of Anzio | World War II

From January 22, 1944 (starting with the Allied amphibious landing known as Operation Shingle) to June 5, 1944, the Battle of Anzio was fought in the Italian Campaign of World War II (ending with the capture of Rome). German forces in the Anzio and Nettuno areas fought back against the operation. The operation was led by Major General John P. Lucas of the United States Army, commanding the United States VI Corps to outflank German soldiers at the Winter Line and launching an attack on Rome.

The part of surprise and the speed with which the invaders could build up strength and move inland relative to the defenders' reaction time and power were critical to the success of an amphibious landing in that basin, which was primarily made up of reclaimed marshland and surrounded by mountains. Any delay could result in the defenders occupying the hills and trapping the invaders. Lieutenant General Mark W. Clark, commander-in-chief of the United States Fifth Army, was aware of the danger. Still, he did not convey his understanding to his subordinate Lucas, who preferred to take his time entrenching against an impending counterattack. As a result, the initial landing was utterly unexpected, with minimal resistance, and a jeep patrol even made it to Rome's outskirts. Lucas, however, who had little faith in the operation's success as planned, failed to make use of the element of surprise and instead waited until his position was sufficiently reinforced and he had sufficient strength before moving forward.

While Lucas solidified, the German commander in the Italian theatre, Field Marshal Albert Kesselring, deployed whatever force he could spare to form a defensive ring around the beachhead. Every Allied position was visible to his artillery batteries. The Germans also turned off the drainage pumps and inundated the reclaimed marsh with saline water to trap the Allies and destroy them by plague. As a result, a downpour of shells fell for weeks on the beach, the marsh, the harbour, and anything else visible from the hills, with little distinction between forward and back positions.

Lucas was relieved and went home after a month of fierce but inconclusive warfare. Major General Lucian Truscott, who had previously led the US 3rd Infantry Division, took his post. In May, the Allies erupted. Instead of moving interior to sever German Tenth Army elements fighting at Monte Cassino's lines of communication, Truscott grudgingly diverted his forces northwest towards Rome, which was seized on June 4, 1944, on Clark's instructions. As a result, the German Tenth Army forces fighting at Cassino were able to retire and rejoin the remainder of Kesselring's points north of Rome, regroup, and fight their way to his next central defensive position on the Gothic Line.

Allied soldiers were stranded at the Gustav Barrier, a defensive line spanning Italy south of the strategic objective of Rome, near the end of 1943, following the Allied invasion of Italy. The central Italian topography had proven to be ideal for defence, and Field Marshal Albert Kesselring took full advantage of it. In December 1943, while recovering from illness in Marrakesh, British Prime Minister Winston Churchill conceived Operation Shingle. He designed to land two divisions at Anzio and conquer Rome, avoiding German forces in central Italy, which was the strategic goal of the ongoing Battle of Rome. By January, he had recovered and was hounding his superiors for an attack strategy, accusing them of not wanting to fight and simply wanting to collect money and rations. Since October, General Harold Alexander, commander of the Allied Armies in Italy, considered a five-division proposal. The 5th Army, on the other hand, lacked both troops and transportation. To divert German soldiers away from Monte Cassino, Clark advocated landing a reinforced division. Instead of failing in the same way, the second landing would hold "the shingle" for a week in the hopes of a breakthrough at Cassino, earning the operation the moniker Shingle.

The beachhead at Anzio is located at the northwestern end of a restored wetland known as the Pontine Marshes, now known as the Pontine Fields (Agro Pontino). Previously inhospitable due to malaria-carrying mosquitoes, troops marched across it as swiftly as possible on the Via Appia military road in Roman times. The sea was on one side of the marsh, and mountains on the other: the Monti Albani, Monti Lepini, Monti Ausoni, and further south, the Monti Aurunci (where the allies had been brought to a halt before Monte Cassino). Monti Laziali, the mountains of Lazio, the old Latium, is the collective name for these mountains. Invading forces from the south had to choose between crossing the marsh or risking entrapment by taking the only alternative road to Rome, the Via Latina, which ran along the eastern sides of the Monti Laziali. Benito Mussolini transformed the wetlands into arable land in the 1930s. Canals and pumping stations were constructed to remove the salty water from the ground. These canals separated the land into personal parcels with new stone dwellings for colonists from northern Italy. Mussolini also established the five cities that were destroyed during the fight.

When Lucian Truscott's 3rd Division was first chosen for the mission, he warned Clark that no one would survive. The position was a death trap. Clark agreed to call off the operation, but Prime Minister Churchill resurrected it. The Americans saw such a landing as a distraction from Cassino, but if they couldn't get through at Cassino, the males at Anzio would be stuck. So Churchill and the British high command planned an outflanking operation that would culminate in the liberation of Rome. General Dwight D. Eisenhower, who was leaving to take control of Operation Overlord, went the decision to Churchill, cautioning him of German unpredictability. To sever German communications and "threaten the rear of the German XIV Panzer Corps," Lucas was to command the US VI Corps in a landing in the Anzio area, followed by an assault into the Alban Hills (under Fridolin von Senger und Etterlin). It was thought that a change like this would divert German soldiers away from the Monte Cassino area, allowing the Allies to get through.

Allied militaries would be able to break through the Gustav Line if Kesselring dragged troops out of the Gustav Line to protect against the Allied assault; if Kesselring did not pull troops out of the Gustav Line, Operation Shingle would threaten to capture Rome and cut off the German units defending the Gustav Line. The Allies believed that even if Germany had sufficient reinforcements to hold both Rome and the Gustav Line, the operation would still help engage forces that may otherwise be deployed on another front. On December 18, 1943, the process was formally cancelled. It was, however, later re-selected.

Clark did not believe he had the numbers to exploit any breakthrough on the southern front. As a result, his strategy was to rely on the south of the onslaught to pull Kesselring's reserves in and allow the Anzio force to break inland fast. It would also reflect Alexander's orders to "... carry out an assault landing on the beaches near Rome to sever enemy lines of communication and strike the rear of the German XIV Corps [on the Gustav Line]." His written directives to Lucas, however, did not reflect this. At first, Lucas had been given orders to "1. Establish a beachhead near Anzio and hold it. 2. Advance to Colli Laziali [Albanian Hills] and secure it. 3. Be ready to make a move on Rome ".  However, Clark's final orders said, "... 2. Advance on Colli Laziali", which gave Lucas a lot of leeways when he wanted to attack the Alban Hills. Both Clark and Lucas' prudence was most likely a result of Clark's experiences during the difficult battle for the Salerno beachhead and Lucas' innate caution arising from his lack of battle experience. Clark and Lucas didn't have complete faith in their superiors or the operating plan. Along with maximum of the Fifth Army staff, they believed Shingle should have been a two-corps or possibly a full-army task. Lucas wrote in his notebook a few days before the attack, "They'll end up bringing me ashore with insufficient soldiers, placing me in a bad situation... Then who will bear the brunt of the blame?" and "[The surgery] had a distinct Gallipoli odour, and the same amateur was still on the coach's bench." The term "amateur" could only have referred to Winston Churchill, the mastermind behind the disastrous Gallipoli landings in World War I and Shingle's supporter.

Availability of Naval Forces

The strategy had several flaws, one of which was the lack of landing ships. The American leaders, in especially, were adamant that the Normandy assault and accompanying landings in southern France should not be delayed. Operation Shingle would necessitate the employment of landing ships, which are required for such missions. Shingle had planned to distribute these assets by January 15th. However, because this was deemed an issue, President Roosevelt allowed the boat to stay until February 5. Shingle had access to only enough tank landing ships (LSTs) to land a single division at first. Eventually, enough was made available at Churchill's request to land two divisions. Although U.S. 5th Army intelligence badly overestimated the German 10th Army's fighting capacity at the time, anticipating that many of their units would be worn out by the defensive engagements waged since September, Allied intelligence believed that five or six German divisions were in the vicinity.

Southern Attack

The attack on the Gustav Line by the Fifth Army began on January 16, 1944, in Monte Cassino. Although the operation futile to break through, it partially achieved its primary goal. The Gustav Line's commanding officer, Heinrich von Vietinghoff, requested reinforcements, and Kesselring dispatched the 29th and 90th Panzergrenadier Divisions from Rome.

Initial Landings

On January 22, 1944, the landings began. Even though the opposition was expected, as was the case at Salerno in 1943, the initial landings were largely unopposed, except for a few futile Luftwaffe strafing runs. As a result, 36,000 soldiers and 3,200 vehicles had landed on the beaches by midnight. Thirteen Allied forces were killed, and 97 were injured, with around 200 Germans taken as POWs. The 1st Division advanced 2 miles (3 kilometres) inland, the Rangers took Anzio's harbour, the 509th PIB took Nettuno, and the 3rd Division advanced 3 miles (5 kilometres) inland. The command of the Italian resistance organization met with the Allied General Headquarters in the early days of operations, offering to guide the Allied Force through the Alban Hills territory, but the Allied Command declined.

After the Landings

Lucas' bosses expected him to take some form of harsh response. The goal of the landing was to confuse the German defences on the Winter Line by exploiting their exposed rear and causing them to retreat north past Rome. On the other hand, Lucas put more soldiers and supplies into his small bridgehead, bolstering his defences. This conduct enraged Winston Churchill, who expressed his displeasure with it. "I had thought we'd fling a wildcat into the shore, but all we got was a stranded whale," he explained. Lucas' decision is still up for debate. According to John Keegan, a well-known military historian, "Lucas' spearheads would have arrived if he had risked rushing at Rome on the first day, albeit they would have been smashed quickly. Despite this, he may have made claims well inland."

Nonetheless, "Lucas was not optimistic about the operation's strategic strategy. In addition, he might easily argue that his interpretation of Clark's directions was reasonable. It would have been realistic for Lucas to consider the beachhead insecure with two divisions landing and against two or three times as many Germans." According to Keegan, though, Lucas' actions "achieved the worst of both worlds," exposing his soldiers to risk while imposing none on the enemy.

Response of Axis forces

The landings were announced to Kesselring at 3 a.m. on January 22. Even though the landings were unexpected, Kesselring had prepared contingency plans to deal with landings in all potential places. The projects relied on each of his divisions forming a motorized fast reaction unit (Kampfgruppe) that could move quickly to meet the threat and buy time for the remainder of the fortifications to be set up. Accordingly, he launched Operation "Richard" at 5 a.m., ordering the 4th Parachute Division's Kampfgruppe and the Hermann Göring Panzer Division to protect the routes from Anzio to the Alban Hills via Campoleone and Cisterna, with 20,000 defensive troops expected by the conclusion of the first day. In addition, he demanded that OKW send reinforcements. They responded by ordering the equivalent of more than three divisions from France, Yugoslavia, and Germany and releasing three more divisions in Italy under OKW's direct command Kesselring. In addition, General Eberhard von Mackensen (Fourteenth Army) and General Heinrich von Vietinghoff (Tenth Army – Gustav Line) were ordered to give him fresh reinforcements later that morning.

A few days before, German forces in the area had been ordered to bolster the Gustav Line. Accordingly, the 3rd Panzer Grenadier and 71st Infantry Divisions and the bulk of the Luftwaffe's Hermann Göring Panzer Division were hurried to Anzio and Nettuno from the southern front on their way there. Kesselring first believed that a successful defence would be impossible if the Allies launched a big attack on January 23 or 24. Yet, by the end of January 22, the absence of proactive action had convinced him that defence was possible. Nonetheless, only a few more defenders arrived on January 23, despite Lieutenant-General Alfred Schlemm and his 1st Parachute Corps headquarters on the evening of January 22 bringing more excellent organization and purpose to the German defensive preparations. As a result, the Germans had approximately 40,000 troops in defensive positions by January 24. The beachhead was surrounded by three divisions three days after the landings. The 3rd Panzer Grenadier Division to the centre, the 4th Parachute Division to the west in front of Alban Hills, and the Hermann Göring Panzer Division to the east. On January 25, Von Mackensen's 14th Army took command of the defence. Eight German divisions were stationed along the beachhead's defence line, and five more divisions were on their way to the Anzio area. On January 28, Kesselring authorized an attack on the beachhead, but it was postponed until February 1.

Liberty Ship Involvement

During the Battle of Anzio, Liberty ships, which were never designed to be warships, were involved in some action. From 22 to 30 January 1944, the SS Lawton B. Evans was repeatedly bombarded by shore guns and aircraft for eight days. It was flooded with shrapnel, machine-gun fire, and explosives for a long time. Finally, the gun crew fought back with shellfire and shot down five German planes.

Allied Offensive

By January 29, Allied forces on the beachhead totalled 69,000 men, 508 guns, and 208 tanks, while defending Germans totalled 71,500. On January 30, Lucas launched a two-pronged assault. One force would cut Highway 7 at Cisterna before heading east into the Alban Hills, while the other would head northeast up the Via Anziate towards Campoleone.

Campoleone: The British 1st Division gained ground but fell short of capturing Campoleone, ending the action in an exposed salient reaching up the Via Anziate.

Cisterna: The major attack by the US 3rd Division took terrain up to 3 miles deep on a seven-mile wide front, but it failed to break through and capture Cisterna. Two Ranger battalions staged a daring clandestine push into Cisterna on the right, ahead of the main attack (see Battle of Cisterna). They were engaged and cut off when daylight arrived due to faulty intelligence. Following that was a bloody confrontation with parts of Hermann Göring's Division. Rangers began surrendering in small groups or individually, provoking others to shoot them on their authority. Six men from the 1st and 3rd Ranger Battalions returned to Allied lines, while 761 were killed or captured.

German Counterattacks

By early February, the German forces in the Fourteenth Army numbered over 100,000 men, divided into two Army Corps: Schlemm's 1st Parachute Corps and Lieutenant General Traugott Herr's LXXVI Panzer Corps. By this time, the Allied forces had grown to 76,400 men counting the newly reached British 56th Infantry Division, under the command of Major-General Gerald Templer, which came entirely on February 16. On the afternoon of February 3, after conducting exploratory probes on the Campoleone salient, German forces launched a comprehensive counterattack around 23:00 to reduce the salient and "iron out" the front line. Rather than using a swift, focussed attack to cut it off, Von Mackensen planned for the salient to be ground away. However, the front line's cohesion had been entirely shattered a few hours after the offensive began, and the combat for the salient had given place to minor unit actions swaying back and forth through the gullies. The situation was becoming more severe on February 4th, with the 1st Battalion, Irish Guards (of the 24th Guards Brigade) having only one cohesive rifle company left, and the 6th Battalion, Gordon Highlanders (of the 2nd Brigade) beginning to crumble and later losing three complete companies as prisoners. Nevertheless, Lucas was able to boost the British 1st Division's defences with the recently arrived 168th Brigade even though the salient's base was nearly broken.

The 3rd Brigade had been assigned with holding the salient tip on the road leading north of Campoleone, 2 miles long and 1,000 yards wide. Still, after the German raids in the initial hours of 4 February, the 2nd Battalion, 1st Battalion, Sherwood Foresters, King's Shropshire Light Infantry, and 1st Battalion, Duke of Wellington's Regiment were cut off. They maintained the position all day, sustaining significant casualties, but were eventually ordered to withdraw and, with the help of artillery and a successful assault launched by the London Scottish, of the 168th Brigade, reinforced by the 46th Royal Tank Regiment, completed a fighting withdrawal to the Factory at 5 p.m. (46 RTR). From February 5 to 7, both sides used massive artillery concentrations and bombers to disrupt the other, and the Germans resumed their attack at 21:00 on February 7.

The fighting was fierce once more, and they infiltrated among the 5th Battalion, Grenadier Guards and the 2nd Battalion, North Staffordshire Regiment and almost surrounded them; Major William Sidney, a company commander-in-chief in the 5th Grenadier Guards, was later bestowed the Victoria Cross for his leadership of British counterattacks during this period. Nevertheless, the Allies were gradually pushed out of the salient, and by February 10, they had been pushed out. On February 11, Lucas ordered attacks to reclaim the lost ground, but the Germans, who a radio intercept had forewarned, repelled the Allies' ill-coordinated attack.

The Germans launched a second onslaught (Operation Fischfang) down the Via Anziate line on February 16, backed up by Tiger tanks. They overran the 167th Brigade of the newly arriving 56th (London) Division, effectively destroying X Company of the 8th Battalion, which was shortened from roughly 125 men to a single officer and ten other ranks, and Y Company to one officer and ten soldiers. Second Lieutenant Eric Waters’ son Roger Waters of Pink Floyd wrote a song (When the Tigers Broke Free) in tribute to his father and depicts his death, was one of the men slain.

The Allies' Final Beachhead Line (planned defences roughly on the line of the original beachhead) was under attack by February 18 after intense combat. Several attacks were conducted against the 1st Battalion, Loyal Regiment (2nd Brigade), and they lost a company, were overrun and suffered 200 losses the next day. On the same day, Major-General Ronald Penney, the British 1st Division's General Officer Commanding (GOC), was wounded by shellfire. The Division was provisionally instructed by Major-General Templer, the GOC 56th (London) Division, which had arrived complete. The German advance was halted by a counterattack led by VI Corps reserves, and on February 20, Fischfang came to an end with both sides weary. The Germans had suffered 5,400 casualties during Fischfang, while the Allies had suffered 3,500. Since the first landings, both had suffered about 20,000 losses, and it was "by far the heaviest density of destruction in the Italian campaign, probably in the entire war." On the same day, the light cruiser HMS Penelope was lost by two torpedoes while returning to Anzio, losing 417 men. Despite the men' exhaustion, Hitler urged that the 14th Army continue to strike. Despite Kesselring's and von Mackensen's reservations, a new assault was launched on February 29, this time against the LXXVI Panzer Corps' front around Cisterna. The 14th Army suffered an additional 2,500 casualties due to this push.

Some RSI Italian soldiers fought at the Anzio-Nettuno area, mainly since March; land units were part of the German 14th Army; only the "Nembo" Battalion's paratroopers had been there since February, fighting in the German counter-offensive. The "Barbarigo" Battalion (from the Decima Flottiglia MAS) joined the fight near the Canale Mussolini in March.

Lucas Replaced

Churchill had remained irritated by Lucas' apparent indifference. On February 10, he wrote to General Alexander, encouraging him to use his power. On February 14, Alexander visited the beachhead to notify Lucas that he wished for an escape as soon as the tactical situation permitted. After his visit, Alexander wrote to Alan Brooke, Chief of the Imperial General Staff, saying, "I am displeased with VI Corps Headquarters." They are pessimistic and lack the motivation and passion for getting things done. They appeared to be depressed as a result of the occurrences.

On February 15, Lucas wrote in his diary, "I'm afraid the top side isn't delighted with my job... They are understandably dissatisfied that I could not expel the Huns from Italy, but there was no military reason for me to do so. Shingle, in truth, has no military significance. Nevertheless, on February 16, it was decided to nominate two deputies under Lucas, Lucian Truscott and the British Major-General Vyvyan Evelegh, at a high-level conference convened by Alexander and joined by Mark W. Clark and Henry Maitland Wilson, commander Associated Force HQ. On February 22, Clark swapped Lucas with Truscott, assigning Lucas as deputy commander Fifth Army until suitable employment in the United States could be found.

Both sides had realized that a conclusion would have to wait until the spring, so they retreated to a defensive posture of intense patrolling and artillery duels while they laboured to replenish their fighting skills. In preparation for the following spring, Kesselring ordered the construction of the Caesar C line, which would run from the mouth of the Tiber just south of Rome over Albano, dodging south of the Alban Hills to Valmontone, and crossways Italy to the Adriatic shore at Pescara, behind which the 14th Army and, to their left, the 10th Army could withdraw if necessary. Meanwhile, Lucian Truscott, who had replaced Lucas as commander of VI Corps on February 22 after being promoted from command of the US 3rd Infantry Division, worked with his staff on tactics for a decisive invasion as part of a general offensive Alexander was planning for May, which would comprise a major attacking on the Gustav Line, Operation Diadem. The plan's goal was to completely engage Kesselring's soldiers with a strong offensive, eliminating the Germans' possibility of removing forces from Italy to redeploy elsewhere. It was also meant to trap the German 10th Army between the Allied troops moving through the Gustav Line and the VI Corps pressing inland from Anzio.

The 2nd Italian SS "Vendetta" Battalion and the 29th Italian SS Rifle Battalion were dispatched to the Anzio beachhead to combat the Anglo-American forces. Dispersed throughout German battalions, the German commanding commanders gave the Italian companies favourable assessments. Former Blackshirt Lieutenant-Colonel Degli Oddi's "Vendetta" assisted in defeating the US 3rd Infantry Division's determined attempt to overrun their positions and capture several prisoners. Because of their performance at Anzio, they were designated as Waffen-SS troops, with all the responsibilities and powers it entailed.

On both sides, divisions shifted dramatically during the next few weeks. On March 23, 1944, the 504th Parachute Infantry Regiment of the United States, which had fought bravely but incurred significant losses, was withdrawn to England. The US 34th Infantry Division arrived in Anzio in March, followed by the US 36th Infantry Division in early May. On the British adjacent, the 24th Guards Brigade of the British 1st Infantry Division was replaced by the 18th Infantry Brigade in the first week of March (from the British 1st Armoured Division in North Africa). In just over two months at Anzio, the Guards Brigade had sustained catastrophic losses (almost 2,000 men out of an initial strength of over 2,500). After suffering tremendous losses (one of its battalions, the 7th Ox and Bucks of the 167th (London) Brigade, was reduced from 1,000 to 60), the British 5th Infantry Division relieved the 56th (London) Infantry Division in late March. By late May, the bridgehead had 150,000 Allied forces, including five US and two British divisions, battling five German divisions. The Germans were securely dug into their prepared positions, but they lacked officers and NCOs in large numbers, and by the time of the late May onslaught, they had no reserves which had all been directed south to the Gustav fighting.

Even though Alexander's overall plan for Diadem called for VI Corps to attack inland and cut Route 6, Clark instructed Truscott to prepare alternatives and be ready to switch from one to the other at a moment's notice. In one of Truscott's four scenarios, Operation Buffalo planned an attack via Cisterna, into the gap in the hills, and across Route 6 at Valmontone. On the other hand, Operation Turtle envisaged the main thrust to the left of the Alban Hills, through Campoleone, Albano, and Rome. On May 5, Alexander chose Buffalo and sent orders to Clark to that end.

On the other hand, Clark was adamant that VI Corps go straight to Rome, as indicated by his subsequent writing: "We not only desired but also believed that we deserved, the dignity of seizing Rome. Not only did we want to be the first army to capture Rome from the south, but we also required to make sure that everyone back home knew it was the Fifth Army who accomplished it and how much it cost." Furthermore, he argued to Alexander that VI Corps lacked the strength to trap the German 10th Army. Instead of stating his requirements clearly, Alexander was conciliatory, implying that a push on Rome was still possible if Buffalo ran into problems. "The capture of Rome is the only significant aim," Clark told Truscott on May 6, "and to be prepared to execute Turtle as well as Buffalo."

Truscott's planning for Buffalo was meticulous: on the left, the British 5th and 1st Divisions would invade along the coast and up the Via Anziate, pinning the German 4th Parachute, 65th Infantry, and 3rd Panzergrenadier in place, while the US 1st Armored, 45th Infantry, and 3rd Infantry Divisions would launch the main attack, engaging the German 362nd and 715th Infantry Divisions and striking The 1st Special Service Force would guard the American assault's flank on the Allies' extreme right.

On 23 May 1944 around 5:45 a.m., 1,500 Allied artillery pieces began bombarding. The guns paused for forty minutes as close air support attacked, then resumed as the Infantry and armour advanced. The 1st Armored Division lost 100 tanks on the first day, while the 3rd Infantry Division suffered 955 casualties. The Germans were also hit hard, with the 362nd Infantry Division losing half of its fighting strength. During the breakout at Anzio, Italy, on May 22, 1944, men from 'D' Company, 1st Battalion, Green Howards, part of the British 5th Division's 15th Brigade, occupy a captured German communications trench.

Mackensen was sure that the Allies' primary drive would be via the Via Anziate, and the British trick on May 23 and 24 did nothing to change his mind. On the other hand, Kesselring was sure that the Allies intended to take Route 6 and dispatched the Hermann Göring Panzer Division from Livorno to Valmontone to keep Route 6 open for the Tenth Army was retreating up this road from Cassino.

Cisterna fell to the 3rd Division in the afternoon of May 25, which had to walk house to house blinking out the German 362nd Infantry, who had refused to retire and, as a result, had almost vanished by the end of the day. By the end of May, portions of the 3rd Infantry had come within 3 miles of Valmontone and were in contact with the Herman Göring Division forces, which had just begun to arrive from Leghorn. Even though VI Corps had lost over 3,300 men in the three days of fighting, Truscott was self-assured that a concerted attack by the 1st Armored and 3rd Infantry Divisions the next day would put his troops astride Route 6.

On May 25, Truscott got additional orders from Clark via Brigadier General Don Brand, his Operations Officer. These were intended to carry out Operation Turtle and turn the primary attack line 90 degrees to the left. Most significantly, while the attack on Valmontone and Route 6 would continue, the 1st Armored Division would retire to prepare for the planned breakthrough along the new line of attack, leaving the 3rd Division to pursue Valmontone with the help of the 1st Special Service Force. By the time Clark told Alexander of these developments late on May 26, orders had already been changed.

Truscott was taken aback at the time, noting subsequently, "I was astonished." It was not the moment to drive to the northwest, where the enemy was still strong; we needed to focus all of our resources on the Valmontone Gap, where the retreating German army might be destroyed. I would not obey the order unless I first spoke with General Clark in person. However, he was not on the foothold and could not be reached even by the radio. Such was the order that diverted the beachhead forces' main effort away from the Valmontone Gap and prevented the German Tenth Army from being destroyed. The order went into detail on the 26th.

After that, he wrote: I have never doubted that if General Clark had stayed valid to General Alexander's orders and not changed the direction of my attack to the northwest on May 26, the planned purposes of Anzio would have been fully realized. Being first in Rome was a poor substitute for the opportunity that had been missed.

Kesselring deployed components of four divisions into the Velletri gap on May 26, as the VI Corps began its tricky manoeuvre, to stop the assault on Route 6. They fought the 3rd Division for four days before finally withdrawing on May 30, after keeping Route 6 open and allowing seven divisions from the 10th Army to evacuate and travel north of Rome. Monte Artemisio has two peaks: Monte Peschio (939 m) and Maschio d'Ariano (812 m) (891 m)

Little headway was achieved on the new offensive axis until the 1st Armored arrived on May 29, when the front moved to the primary Caesar C Line defences. Despite this, an early breakthrough appeared doubtful until Major General Fred L. Walker's 36th Division discovered a weakness in the Caesar Line at the junction of the 1st Parachute Corps and the LXXVI Panzer Corps on May 30. As they ascended the steep slopes of Monte Artemisio, they threatened Velletri from behind, forcing the defenders to retreat. It was a watershed moment, and von Mackensen tendered, and Kesselring accepted his resignation.

To add to the pressure, Clark assigned the U.S. II Corps, which had joined up with VI Corps on May 25 after battling its way along the coast from the Gustav Line, to strike around the right-hand side of the Alban Hills and march up Route 6 to Rome.

The Caesar Line collapsed on June 2 due to the mounting pressure, and the 14th Army began a fighting withdrawal through Rome. Fearing a repeat of Stalingrad, Hitler had ordered Kesselring to order "no defence of Rome" on the same day. The rearguards were gradually overwhelmed over the next day, and Rome was entered in the early hours of June 4th, with Clark holding an impromptu press conference on the steps of the Capitoline Hill's Town Hall. He ensured that the event was purely an American affair by stationing military police at traffic crossings and refusing admission to the city by British military troops.

Although the debate rages about what may have happened if Lucas had been more proactive from the outset, most commentators agree that the Anzio strategy was defective. They doubt that the initial invasion of just over two infantry divisions, with no supporting armour, had the strength to accomplish the objectives: cutting Route 6 and then holding off the anticipated counterattacks while Kesselring redeployed his forces.

Churchill's The Second World War, Volume 5, is littered with implied criticisms of Lucas, who is blamed for the failure due to his caution. Kesselring stated his assessment after the war: Overextending themselves would have been the Anglo-American fate. Initially, the landing force was small, with only soldiers and no armour division. That was your main error: it was a half-measure of an offensive. "The real course of events was probably the most advantageous in the end," Field Marshal Sir Harold Alexander wrote in his Official Dispatch.

The operation was defended by Churchill, who believed that adequate forces were available. He had undoubtedly made significant political efforts to get critical resources, including the extra LSTs required to carry a second division to shore and specific attack formations such as the 504th Parachute Infantry Regiment. He said that regardless of the operation's tactical outcome, there was an instant strategic benefit to the war effort. Following the landings, the German High Command decided to abandon its intentions to send five of Kesselring's strongest divisions to Northwestern Europe. Instead, it aided the future Operation Overlord. When the Soviet Red Army was experiencing massive losses on the Eastern Front, Churchill had to ensure that the British-dominated forces in Italy were contributing to the war effort. In Anzio, Italy, on March 1, 1944, Private Phillip Johnson of the 2/6th Battalion, Queen's Royal Regiment (West Surrey), inspects British graves.

Operation Diadem (during which the US Fifth Army and the British Eighth Army suffered 44,000 losses) failed to destroy the German 10th Army due to Clark's change of plan. It also sentenced the Allies to another year of bloodshed in Italy, particularly along the Gothic Line, from August 1944 to March 1945.

The most significant loss was that if the main effort of the US Army VI Corps had proceeded on the Valmontone axis from May 26, Clark would have been able to reach Rome far faster than if he had taken the path northwest from Cisterna. The VI Corps also had the option of cutting Highway 6 and putting far more pressure on the 10th Army than it did. Alan Whicker, a British Army Film and Photo Unit war correspondent who was present during the fighting, later said: Alexander's plan was for the Fifth Army to drive east after breaking out of Anzio, cutting off Kesselring's escape route to the north and trapping much of his Tenth and Fourteenth Armies. The mission began well, but the Fifth Army was abruptly redirected and moved north towards Rome, only six kilometres from shutting their trap at Frosinone. Unfortunately, the trap had been left unlocked. General Mark Clark was so eager for the world to see photos of him as Rome's saviour that he let the armies of a jubilant Kesselring escape.

He had disobeyed Field Marshall Alexander's orders in a militarily and insubordinate choice. The worst of the war, this miscalculation cost us a dramatic victory, extended the war by several months, and earned Mark Clark the scorn of fellow American and British generals. They saw an operation in Italy that could have won the battle squandered away at the expense of countless Allied deaths because of one man's preoccupation and ego.

According to Alan Whicker, "Hitler would have shot General Mark Clark if he had served in the German army."

Clark received similar treatment from the media. The "advance" was demoted to the back pages just two days after his staged press conference on Rome's Capitolium, as reporting on the Normandy D Day invasion took centre stage on June 6.