June 13th, 1939 (TUESDAY)
U.S.A.: The aircraft carrier USS Saratoga (CV-3) and the fleet oiler USS Kanawha (AO-1) complete a 2-day underway refuelling test off the coast of southern California, thereby demonstrating the feasibility of refuelling carriers at sea, a technique that will enable the US Navy to conduct operations in areas where bases are not available.