The rapid fall of France in early 1940 caused alarm in the western hemisphere that French possessions in the West Indies might fall into German hands. American planners drew up contingency plans to take these isles by force if necessary. In the event of such an invasion, Upshur and her sisters in Destroyer Squadron 30 were slated to screen the counter-battery and gunfire support group built around , , and . The crisis abated by late 1940. In between the routine neutrality patrol assignments and training, Upshur was called upon to perform a special escort mission. On 23 December 1940, the heavy cruiser Tuscaloosa departed Norfolk with William D. Leahy, Ambassador to Vichy France, and his wife, embarked, bound for Lisbon, Portugal. Upshur and escorted the heavy cruiser, until they were detached on Christmas Day to return to Norfolk while the cruiser proceeded on, unescorted, on her diplomatic mission. In March 1941, the Support Force was established for the United States Fleet, under the command of Rear Admiral Arthur LeRoy Bristol. Based at Narragansett Bay, this group prepared for assignment to "distant seas" and was formed around , , , and . Four patrol plane squadrons and three destroyer squadrons—the last including Upshur—rounded out the Support Force. Over the ensuing months, Upshur operated alternately out of Naval Station Argentia, Newfoundland; Newport, Rhode Island; Philadelphia; Narragansett Bay; Boston; and Reykjavík, Iceland, after its occupation by the United States that summer. On 11 September, the destroyer departed Argentia, bound for a rendezvous with an outward-bound convoy headed for the British Isles. Five days later, a convoy of 50 merchantmen of British and Allied nationalities—classified as HX 150 —put to sea from Halifax, Nova Scotia, escorted locally by Canadian units. On 17 September, about out of Argentia, the American escort group under Captain Morton L. Deyo, which included Upshur, met up with the British convoy. The ensuing days witnessed the five American destroyers shepherding the convoy towards the "Mid-Ocean Meeting Point" (MOMP). Upshur steamed on the port side of the convoy, out, searching with her sound equipment on a 30-degree sector during the day, and patrolling out at night. The Americans brought the convoy safely to the MOMP, where British ships— two destroyers and four corvettes—picked up the England-bound ships. The five American destroyers then convoyed the Iceland-bound section of the convoy to Reykjavík. This convoy was the first one assisted by the