The Crossmen Drum and Bugle Corps was founded on October 1, 1974, by a merger of two suburban Philadelphia drum and bugle corps, the Keystone Regiment and the 507 Hornets. The name "Crossmen" was chosen, from a list of 43 proposed names, by the members of the new corps in recognition of American Legion Post 507, which was named in honor of World War I veteran John Welsey Cross. Beginning in Delaware County, Pennsylvania, the corps has, over the years, been based in several other communities. Their longest stays were in West Chester, Pennsylvania and Newark, Delaware.