The Battle of Anzio was a battle of the Italian Campaign of World War II that commenced 22 January 1944. The battle began with the Allied amphibious landing known as Operation Shingle, and ended on 4 June 1944, with the invasion of Rome. The operation was opposed by German and by Italian Repubblica Sociale Italiana (RSI) forces in the area of Anzio and Nettuno.
Allied landings on the Italian mainland began in September 1943, and after slow gains against German resistance, the progress was stopped in December 1943 at the German defensive Gustav Line, south of Rome.
The operation was initially commanded by Major General John P. Lucas, of the U.S. Army, commanding U.S. VI Corps with the intent to outflank German forces at the Winter Line and enable an attack on Rome.
The success of an amphibious landing at that location, in a basin consisting substantially of reclaimed marshland and surrounded by mountains, depended on the element of surprise and the swiftness with which the invaders could build up strength and move inland relative to the reaction time and strength of the defenders. Any delay could result in the occupation of the mountains by the defenders and the consequent entrapment of the invaders. The initial landing achieved complete surprise with no opposition and a jeep patrol even made it as far as the outskirts of Rome. However, Lucas, who had little confidence in the operation as planned, failed to capitalize on the element of surprise and delayed his advance until he judged his position was sufficiently consolidated and he had sufficient strength.
While Lucas consolidated, Field Marshal Albert Kesselring, the German commander in the Italian theatre, moved every unit he could spare into a defensive ring around the beachhead. His artillery units had a clear view of every Allied position. The Germans also stopped the drainage pumps and flooded the reclaimed marsh with salt water, planning to entrap the Allies and destroy them by epidemic. For weeks a rain of shells fell on the beach, the marsh, the harbour, and on anything else observable from the hills, with little distinction between forward and rear positions.
After a month of heavy but inconclusive fighting, Lucas was relieved and sent home. His replacement was Major General Lucian Truscott, who had commanded the U.S. 3rd Infantry Division. The Allies broke out in May. But, instead of striking inland to cut lines of communication of the German Tenth Army's units fighting at Monte Cassino, Truscott, on Clark's orders, turned his forces north-west towards Rome, which was captured on 4 June 1944. As a result, the forces of the German Tenth Army fighting at Cassino were able to withdraw and rejoin the rest of Kesselring's forces north of Rome, regroup, and make a fighting withdrawal to his next major prepared defensive position on the Gothic Line.
The battle was costly, with 24,000 U.S. and 10,000 British casualties.
At the end of 1943, following the Allied invasion of Italy, Allied forces were bogged down at the Gustav Line, a defensive line across Italy south of the strategic objective of Rome. The terrain of central Italy had proved ideally suited to defense, and Field Marshal Albert Kesselring took full advantage.
Operation Shingle was originally conceived by British Prime Minister Winston Churchill in December 1943, as he lay recovering from pneumonia in Marrakesh. His concept was to land two divisions at Anzio, bypassing German forces in central Italy, and take Rome, the strategic objective of the current Battle of Rome. By February he had recovered and was badgering his commanders for a plan of attack, accusing them of not wanting to fight but of being interested only in drawing pay and eating rations. General Harold Alexander, commander of the Allied Armies in Italy, had already considered such a plan since October using five divisions. However, the 5th Army did not have the troops nor the means to transport them. Clark proposed landing a reinforced division to divert German troops from Monte Cassino. This second landing, however, instead of failing similarly, would hold "the shingle" for a week in expectation of a breakthrough at Cassino, and so the operation was named Shingle.
The Anzio beachhead is located at the northwestern end of a tract of reclaimed marshland, formerly the Pontine Marshes, now the Pontine Fields (Agro Pontino). Previously uninhabitable due to mosquitoes carrying malaria, in Roman times armies marched as quickly as possible across it on the military road, the Via Appia. The marsh was bounded on one side by the sea and the other by mountains: the Monti Albani, the Monti Lepini, the Monti Ausoni, and further south the Monti Aurunci (where the allies had been brought to a halt before Monte Cassino). These mountains are collectively referenced by the name Monti Laziali, the mountains of Lazio, the ancient Latium. Invading armies from the south had the choice of crossing the marsh or taking the only other road to Rome, the Via Latina, running along the eastern flanks of the Monti Laziali, risking entrapment. The marshes were turned into cultivatable land in the 1930s under Benito Mussolini. Canals and pumping stations were built to remove the brackish water from the land. These canals divided the land into personal tracts with new stone houses for colonists from northern Italy. Mussolini also founded the five cities destroyed by the battle.
When Lucian Truscott's 3rd Division was first selected for the operation, he pointed out to Clark that the position was a death trap and there would be no survivors. Agreeing, Clark canceled the operation, but Churchill revived it. The two allies had different concepts: the Americans viewed such a landing as another distraction from Cassino, but if they could not break through at Cassino, the men at Anzio would be trapped. Churchill and the British high command envisioned an outflanking movement ending with the capture of Rome. Mediterranean Theatre commander General Dwight D. Eisenhower, leaving to take command of Operation Overlord, left the decision up to Churchill with a warning about German unpredictability.
The final plan called for Lucas to lead the US VI Corps in a landing in the Anzio area, followed by an advance into the Alban Hills, to cut German communications and "threaten the rear of the German XIV Panzer Corps" (under general Fridolin von Senger und Etterlin). It was hoped that such an advance would draw German forces away from the Monte Cassino area and facilitate an Allied breakthrough.
Planners argued that if Kesselring (in charge of German forces in Italy) pulled troops out of the Gustav Line to defend against the Allied assault, then Allied forces would be able to break through the line; if Kesselring didn't pull troops out of the Gustav Line, then Operation Shingle would threaten to capture Rome and cut off the German units defending the Gustav Line. Should Germany have adequate reinforcements available to defend both Rome and the Gustav Line, the Allies felt that the operation would nevertheless be useful in engaging forces which could otherwise be committed on another front. The operation was officially cancelled on 18 December 1943. However, it was later reselected.
Clark did not feel he had the numbers on the southern front to exploit any breakthrough. His plan therefore was relying on the southern offensive drawing Kesselring's reserves in and providing the Anzio force the opportunity to break inland quickly. This would also reflect the orders he had received from Alexander to "... carry out an assault landing on the beaches in the vicinity of Rome with the object of cutting the enemy lines of communication and threatening the rear of the German XIV Corps [on the Gustav Line]." His written orders to Lucas did not really reflect this. Initially Lucas had received orders to "1. Seize and secure a beachhead in the vicinity of Anzio 2. Advance and secure Colli Laziali [the Alban Hills] 3. Be prepared to advance on Rome". Clark's final orders stated "... 2. Advance on Colli Laziali" giving Lucas considerable flexibility as to the timing of any advance on the Alban Hills. It is likely that the caution displayed by both Clark and Lucas was to some extent a product of Clark's experiences at the tough battle for the Salerno beachhead and Lucas' natural caution stemming from his lack of experience in battle.