Born in Bath, Maine on June 17, 1897, the son of a wealthy Bath banker and shipbuilder, Sumner Sewall was educated at Bath public schools before attending Harvard University in 1916.
In the middle of his freshman year, he joined the American Ambulance Field Service and served for six months at the front as an ambulance driver before enlisting in the aviation section of the Army Signal Corps in 1917. A Second Lieutenant in the 95th Squadron of the 1st Pursuit Group, Sewall had become an ace by October 1918, having officially shot down seven German planes and two observation balloons.
For his service in the war, he won the Distinguished Service Cross with Oak Leaf Cluster, the French Legion of Honor, the Croix de Guerre and the Order of the Crown of Belgium.
After the war he attended Yale University for a year and then worked with a rigging crew in the Mexican oil fields, in a bank in Spain, on a sugar plantation in Cuba and as a riveter in the Ford Airplane Factory in Dearborn, Michigan.
The man who would manage Maine’s war effort from 1941-1945 was well-prepared for the task in managerial background as well as military experience. From 1922 to 1924 he engaged in banking in New York City and in 1926, with Juan T. Trippe, President of Pan American Airlines, he helped organize and operate Colonial Air Transport, which held the first air mail contract in the country.
In 1929, he married Helen Ellena Evans, the daughter of Sigismond Embach, a Russian Army Officer, and in 1934 he became a director of United Air Lines.
Sewall’s political career began in 1933 as an Alderman in Bath. He was a State Representative from 1934 to 1936, a State Senator from 1936 to 1940, serving as President for the 1939-40 term and Governor of Maine from 1941 to 1945.
Governor Sewall left office on January 3, 1945 and soon became President of American Overseas Airlines. In 1946 he went to Germany as the Military Governor of Wurtemberg Baden.
Sewall died in Bath, Maine on January 25, 1965.