In 1940, Rear Admiral Ingram assumed command of Cruiser Division 2, subsequently rechristened Task Force 23 and then the Fourth Fleet, stationed in Brazilian waters to secure the South Atlantic against Nazi ships and submarines. Promoted to vice admiral in 1942, he worked closely with Brazilian officials, winning their consent to the construction of American air, naval, and military facilities on Brazilian territory, while helping to upgrade Brazilian naval and air capabilities. Under Ingram's supervision, Ascension Island, 1,000 miles from Brazil's coast, became one of the largest existing air bases, enabling him to launch both aerial and naval attacks on German U-boats. In late 1943, Ingram declared the Atlantic secure from Brazil to West Africa. In November 1944, he was promoted to full admiral and took command of the Atlantic Fleet, protecting shipping routes between North America and the European Theater—and especially troop convoys—against the final German submarine sorties.
Ingram retired from the navy in 1947 to become commissioner of the All-American Football Conference and a vice president of Reynolds Metal Company. He died in San Diego, California, on 10 September 1952.
Conn, Stetson, and Byron Fairchild. The Western Hemisphere: The Framework of Hemispheric Defense. Washington, DC: U.S. Government Printing Office, 1960.; Hughes, Terry, and John Costello. The Battle of the Atlantic. New York: Dial, 1977.; Macintyre, Donald. The Naval War against Hitler. New York: Scribner's, 1961.; Reynolds, Clark G. Famous American Admirals. New York: Van Nostrand Reinhold, 1978.