The invasion of Italy began on September 9, 1943 with the main assault aimed at the Gulf of Salerno. The fifth army was to land, secure Salerno, and to move to one of Europe's largest seaports--Naples. The naval participation for the Mayo consisted of shore bombardment, anti-aircraft support, and escort work.

Sensing the coming invasion, the German's had brought up strong reinforcements in the form of tanks and artillery on ridges overlooking the invasion beaches. The invasion turned out to be a slaughter, with the German's driving the allied forces to the water's edge. Nazi aircraft swept over to bombard and strafe the hapless landing forces.

By noon, Salerno was a deathtrap. The German's had moved 88mm guns on the ridge and were pounding the beaches with devastating effect. By nightfall, American air and shore bombardment pushed the German's back.

By Sept. 13, Nazi Panzer units with Tiger tanks moved up to the front and mauled the Allied landing party. The invasion force soon found themselves being pushed into the sea again. This time the Navy's cruiser Brooklyn and destroyer Mayo moved in to pump salvos at enemy tanks and positions. Enough was enough.

 The Mayo and the Brooklyn moved in and took control of the situation. Nazi machine-gun emplacements were wiped out, artillery pieces clobbered, and tanks were stopped dead in their tracks. It is estimated that the Mayo, with her small draft, moved to within 500 yards of the beachhead. It was here that she received her reputation as a " Tank Buster", as the remains of a German Panzer unit would testify. The Mayo took on the tank unit one on one with the help of a Army spotter plane. The spotter wanted the Mayo to set her guns to rapid fire since her range was so accurate. This resulted in the Mayo firing a shell every 4 seconds at this point during the battle. The USS Mayo and USS Brooklyn were credited with destroying 46 tanks and other artillery pieces in one day. The Mayo's gun barrels were so hot, that the paint and gun boots were scorched and burnt. All her gun barrels had to be replaced after this engagement. According to the gunner's, she fired about 460 5" shells. Navy statistics also reveal that the USS Mayo fired 60% of all 5" artillery at Salerno.

For her participation off Salerno, the Mayo received her first well-earned battle star and a Legion of Merit for Commander Habecker.