The Battle of Anzio was a battle of the Italian Campaign of World War II that took place from January 22, 1944 (beginning with the Allied amphibious landing known as Operation Shingle) to June 5, 1944 (ending with the capture of Rome). The operation was opposed by German forces in the area of Anzio and Nettuno.The operation was initially commanded by Major General John P. Lucas, of the U.S. Army, commanding U.S. VI Corps with the intention being 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. Lieutenant General Mark W. Clark, commander of the U.S. Fifth Army, understood that risk, but he did not pass on his appreciation of the situation to his subordinate Lucas, who preferred to take time to entrench against an expected counterattack. 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 previously 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, reluctantly turned his forces north-west towards Rome, which was captured on June 4, 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 of Cisterna took place during World War II, on 30 January–2 February 1944, near Cisterna, Italy, as part of the Battle of Anzio, part of the Italian Campaign. The battle was a clear German victory which also had repercussions on the employment of U.S. Army Rangers that went beyond the immediate tactical and strategic results of the battle.

During this battle, the 1st, 3rd, and 4th U.S. Army Ranger battalions, the 83rd Chemical Mortar Battalion, and the 509th Parachute Infantry Battalion, which had been brigaded as the 6615th Ranger Force (Provisional) commanded by Colonel William O. Darby, were assigned to support the renewal of an attack by Major General Lucian Truscott's 3rd Infantry Division, which had previously failed to take Cisterna from 25–27 January. The 3rd Division's attack was part of a large offensive by Major General John Lucas's U.S. VI Corps to break out of the Anzio beachhead before German reinforcements could arrive and concentrate for a counterattack.