(Rome-Arno Campaign 22 January to 9 September 1944) U.S. 5th Army advanced 150 miles to the Arno River. The unsuccessful attempt to break the Gustav Line on 22 January was followed by another unsuccessful effort in March when the infantry failed to push through after bombers had endeavored to open the line at Monte Cassino. Allied air power then began a vigorous campaign against railroads, highways, and shipping that supported German forces in Italy. With supply lines strangled, the Germans could not repulse the new drive launched by the Allies in May. German resistance crumbled. By 4 June 1944 the Allies had taken Rome. But the advance ground to a halt against a new defensive line the enemy established along the Arno River.