The renewed attack on Cassino (Operation Diadem) began on the night of 11/12 May, with the brigade's LAA regiments committed to bridges, defiles, assembly areas and artillery positions while enemy aircraft were active in low-level strafing and bombing. However, some LAA units, including 327 Bty, assisted the fireplan by manning 4.2-inch mortars. Once the breakthrough had been achieved and the Allies were advancing along Highway 6 up the Liri Valley there were severe problems in getting the AA guns forward along the heavily congested routes. 12 AA Brigade found itself stretched along of roads protecting the long 'tail', though the "Luftwaffe" made only a few nuisance raids. After the breakout from the Anzio beachhead and the capture of Rome in early June, the Germans pulled back to the Gothic Line.