MS American Leader was a merchant cargo ship which entered service for the United States Lines in 1941.

American Leader was one of five vessels constructed by the Western Pipe and Steel Company from the US Maritime Commission's Type C1-B design.

[5] The detailed building plans were prepared for Western Pipe and Steel by New York naval architect George G.

[1] In the 1930s American shipyards were making a transition from riveting to welding as the main building method[6] and Western had been a pioneer in using these techniques since 1929.

[8] The C1-B cargo ships were constructed with flush full scantling type decks having a raked stem and cruiser stern.

[9] The US Navy had been experimenting with diesel engines for surface ships since 1915 when then-Lieutenant Chester W. Nimitz supervised their construction and installation[10] in the USS Maumee.

American Leader and her four sister C1-B ships at Western were therefore powered by two Busch-Sulzer two-cycle, trunk-piston diesel engines connected to the shaft through electro-magnetic couplings and reduction gears.

[1] American Leader was delivered to the United States Lines 12 June 1941 and began cargo service between New York and the Far East through the Panama Canal.

At Wilmington, California her cargo would begin to include items for a nation at war: mail, magazines, but also several large underground fuel tanks destined for the United States Army Air Force in the Philippines.

Two days later her crew witnessed the destruction of ships in Manila Bay and of the United States Naval Base at Cavite.

At that time the Hilfskreuzer (auxiliary cruiser) Michel of the Deutsche Kriegsmarine (German Navy) had already taken nine ships in the South Atlantic.

She was approximately 800 miles to the west of the Cape of Good Hope when Michel appeared off her starboard bow and opened fire.

[11] On 7 October 1942 the 72 American and British seamen on board Michel were transferred to a Kriegsmarine resupply ship Uckermark and were handed over to the Japanese[14] at Tandjong Priok in early November 1942.

[17] In September, nine American Leader crew members were among the 5,500 prisoners, conscripts, and laborers packed on board the Jun'yō Maru.

On 18 September 1944, sailing in the Indian Ocean about 14 miles from the Sumatran coast, Jun'yō Maru was hit by two torpedoes from HMS Tradewind.

[18] In 1946 the United States Lines acquired the C2-S-B1 cargo ship Twilight from the US Maritime Commission and renamed it American Leader (2) in honor of the first vessel's crew.