The Douglas B-18 Bolo is an American medium bomber which served with the United States Army Air Corps and the Royal Canadian Air Force (as the Digby) during the late 1930s and early 1940s. The Bolo was built by the Douglas Aircraft Company, based on its DC-2, and was developed to replace the Martin B-10.
By 1940, it was considered to be underpowered, to have inadequate defensive armament and to carry too small a bomb load. Many were destroyed during the attacks on Pearl Harbor and the Philippines in December 1941.
In 1942, the B-18 survivors were relegated to antisubmarine, transport duty, and training. A B-18 was one of the first American aircraft to sink a German U-boat, U-654 on 22 August 1942 in the Caribbean.