In 1921 Martin produced its KG.1 variant of the MB-1, with ten purchased by the Navy as torpedo bombers under the designation MBT.

In response to a requirement from the Air Service for a bomber that was superior to the Handley Page O/400, Martin proposed the MB-1 and were rewarded with an initial production contract for six aircraft.

Initial delivery to the Air Service was in October 1918, with the aircraft designated GMB for Glenn Martin Bomber.

On 5 October 1923, the Marine Corps entered an MT, serial number A-5720, in the National Air Races in St. Louis.

[3] They were used in the West Virginian Coal Wars, notably in the Battle of Blair Mountain, as bombers and aerial observers sent in by President Warren Harding.