She escorted convoys between Bizerte, Tunisia and Oran, Algeria. After her first convoy in Bizerte, "Underhill" was ordered out into the Mediterranean Sea where she steamed all night at flank speed, fully illuminated in waters known to be populated with U-boats and overflown by German aircraft. The invasion of southern France was launched a few days later; it is likely "Underhill's" cruise was a diversion or a probe. When returning to Bizerte, she struck a ship sunken in the channel and badly damaged her port propeller and shaft, which was repaired in Oran. After arriving at that port on 27 July, she underwent temporary repairs; then, on 5 August, she departed North Africa. Early on 6 August, she joined the escort of Convoy GUS 47, with which she arrived safely at New York City on 18 August. Six days later, Commander Newcomb relieved Jackson as commanding officer; he would hold the post for the rest of his life.