{|On 8 August 1934, the U.S. Army Air Corps

United States Army Air Corps

The United States Army Air Corps was a forerunner of the United States Air Force. Renamed from the Air Service on 2 July 1926, it was part of the United States Army and the predecessor of the United States Army Air Forces , established in 1941...

 (USAAC) tendered a proposal for a multi-engined bomber to replace the Martin B-10

Martin B-10

The Martin B-10 was the first all-metal monoplane bomber to go into regular use by the United States Army Air Corps, entering service in June 1934...

. The Air Corps was looking for a bomber capable of reinforcing the air forces in Hawaii, Panama, and Alaska. Requirements were that it would carry a "useful bombload" at an altitude of 10000 feet (3 km) for 10 hours with a top speed of at least 200 miles per hour (321.9 km/h).

They also desired, but did not require, a range of 2000 miles (3,218.7 km) and a speed of 250 miles per hour (402.3 km/h).