Seventy tons of fighting strength were added to the Navy air force when Mars, the largest ship ever to fly, was completed. A Martin-built plane, it has four 2,000 horsepower motors, a hull the size of a 15-room house, and a wing-expansion equivalent to the height of a 20-story building. Mars can fly non-stop to Europe and back. Office of War Information photograph. Courtesy of the Library of Congress.