When the Imperial German Government ordered the famous submarine blockade in March of 1917 during World War I, the United States ship, U.S.S Mongolia was armed with three six-inch guns manned by two crews. She was the first ship to sail after the Kaiser's proclamation of the barred zone, and on April 19, 1917, the Mongolia encountered and engaged a German submarine in the English Channel, seven miles southeast of Beachy Head in East Sussex England.

Lester Burnell from South Portland and Baldwin returned home after serving in World War I aboard the U.S.S Mongolia, which in 1919 was serving as a transport ship.