51st (H) Division was designated for the assault landing in Sicily (Operation Husky) on 10 July 1943. 40th LAA Regiment's sea crossing was disrupted when the ships were attacked by U-boats and aircraft. Once ashore the divisional LAA regiments were assigned to beach defence, though they were hampered by the lack of a workable early-warning system. LAA batteries were reduced to firing prepared concentrations, either directional ('Curtains') or overhead ('Umbrellas'), which were ineffective and wasted scarce ammunition. However, the landings made good progress against negligible opposition, and 51st HD was well forward by nightfall. It was then directed to capture Palazzolo Acreide, which it achieved by the end of 12 July. The LAA unit handed over beach defence as the AA brigades began landing. 51st HD took Vizzini on the night of 14/15 July, and was then redirected towards the north east in a high-speed move to Paternò. However, resistance had stiffened, the division was unable to cross the River Simeto, and it had to fight hard to capture Gerbini Airfield. The division went onto the defensive on 21 July.