In early 1930s, Pan Am requested for a flying
boat with capability that could fly across the ocean. Martin's bid of
Model-130 was successful. In 1934, three M-130 were built as Martin Ocean
Transports, but to the public thay were all referred as the China Clipper.
On November 1935, the China Clipper flew the first trans-Pacific airmail
route. Their range and capacity made them prime candidates to fulfill the
over ocean hauling needs of the military during World War II. Beginning in
1942, the two remaining planes were pressed into transport roles for the
United States Navy, but not given a Naval designation and was maintained
their "civilian" status so that they could continue to fly into neutral
ports with secret missions for Allied spies and techicians. The most
special mission was to fly shipments out of Africa with the uranium needed
for the highly top secret Atomic bomb development, the "Manhattan
Project". The Philippine Clipper crashed in San Francisco in 1943, and the
final China Clipper broke up and sank in Trinidad Tobago in 1945.