When first publicly unveiled in January 1954, the Sikorsky S-56 was introduced by its manufacturer as a "giant, twin-engine transport", that represents a "tremendous advance in the art of designing and building helicopters". In fact, the S-56 was the biggest, fastest and most powerful production helicopter in the free world until the introduction of Boeing Vertol's turbine-driven Chinook in 1961. Military production versions of the S-56 were designated by the Marine Corps as ‚HR2S-1‘. Since the HR2S-1 was the second version of the transport helicopter, a ‘2’ was inserted in its designation to indicate this. The Marines, being big on card playing and the ‘2’ card being called a ‘Deuce’, they nicknamed the HR2S-1 ‘the Deuce’