In the early morning hours of 22 January 1944, VI Corps of Lt. Gen. Mark W. Clark's Fifth Army landed on the Italian coast below Rome and established a beachhead far behind the enemy lines. In the four months between this landing and Fifth Army's May offensive, the short stretch of coast known as the Anzio beachhead was the scene of one of the most courageous and bloody dramas of the war. The Germans threw attack after attack against the beachhead in an effort to drive the landing force into the sea. Fifth Army troops, put fully on the defensive for the first time, rose to the test. Hemmed in by numerically superior enemy forces, they held their beachhead, fought off every enemy attack, and then built up a powerful striking force which spearheaded Fifth Army's triumphant entry into Rome in June.
The story of Anzio must be read against the background of the preceding phase of the Italian campaign. The winter months of 1943-44 found the Allied forces in Italy slowly battering their way through the rugged mountain barriers blocking the roads to Rome. After the Allied landings in southern Italy, German forces had fought a delaying action while preparing defensive lines to their rear. The main defensive barrier guarding the approaches to Rome was the Gustav Line, extending I across the Italian peninsula from Minturno to Ortona. Enemy engineers had reinforced the natural mountain defenses with an elaborate network of pillboxes, bunkers, and mine fields. The Germans had also reorganized their forces to resist the Allied advance. On 21 November 1943, Field Marshal Albert Kesselring took over the command of the entire Italian theater; Army Group C, under his command, was divided into two armies, the Tenth facing the southern front and also holding the Rome area, and the Fourteenth guarding central and northern Italy. In a year otherwise filled with defeat, Hitler was determined to gain the prestige of holding the Allies south of Rome.
Opposing the German forces was the Allied 15th Army Group, commanded by Gen. Sir Harold R. L. G. Alexander, with the U.S. Fifth Army attacking on the western and the British Eighth Army on the eastern sectors of the front. In mid-December, men of the Fifth Army were lighting their way through the forward enemy defensive positions, which became known as the Winter Line.
Braving the mud, rain, and cold of an unusually bad Italian winter, scrambling up precipitous mountain slopes where only mules or human packtrains could follow, the Allied forces struggled to penetrate the German defenses. By early January, Fifth Army troops had broken through the Winter Line and had occupied the heights above the Garigliano and Rapido Rivers, from which they could look across to Mount Cassino, with Highway No. 6 curving around its base into the Liri Valley.
Before them were the main ramparts of the Gustav Line, guarding this natural corridor to the Italian capital. Buttressed by snow-capped peaks flanking the Liri Valley, and protected by the rain-swollen Garigliano and Rapido Rivers, the Gustav Line was an even more formidable barrier than the Winter Line. Unless some strategy could be devised to turn the defenses of the Gustav Line, Fifth Army faced another long and arduous mountain campaign.