 Complete the following phrase:  The renewed attack on Cassino began on the night of 1112 May, with HAA guns supplementing the artillery barrage one regiment fired 23,000 rounds in a week, particularly for counter-mortar shoots. The brigades LAA regiments were committed to bridges, defiles, assembly areas and artillery positions, and enemy aircraft were active in low-level strafing and bombing. There were severe problems in getting the AA guns forward along the heavily congested routes. X Corps in the mountains had little use for HAA guns, requiring LAA to defend vital bridges. XIII Corps, on the other hand, after crossing the Rapido river, advanced along Highway 6 up the Liri Valley Operation Diadem on a narrow front, with continual demands for HAA guns in the medium artillery role. 12 AA Bde found itself stretched along of roads protecting the long tail, though the Luftwaffe made only a few nuisance raids. After the breakout from the 