With the outbreak of war in Europe, "Du Pont" was recommissioned 16 October 1939 for duty on the Neutrality Patrol. She patrolled along the east coast, trained reservists, and spent several periods training with submarines out of New London. Between 7 July 1941 and 26 February 1942, she escorted five vital convoys to NS Argentia, Newfoundland, and Iceland, continuing escort and antisubmarine patrol duty in the Atlantic as far north as Argentia and south to the Caribbean. "Du Pont", 15 March 1942, rescued 30 survivors from a torpedoed merchantman. From 8 May 1942 to 19 January 1943, she guarded convoys from New York and Norfolk to Key West and Guantanamo Bay.