Master commandant was a rank within the early United States Navy. Both the Continental Navy and the United States Navy had just two commissioned ranks, lieutenant and captain. Master commandant, who would command smaller vessels, was used unofficially as early as 1799. The rank was made official in 1806 and was changed to "commander" in 1837. The early US Navy had three "grades" of officer who were typically placed in charge of warships: captain; master commandant; and lieutenant, commanding. That structure remains largely in place in the modern US Navy, with the distinct ranks of captain, commander, and lieutenant commander. Master commandant was roughly equivalent to the Royal Navy rank of master and commander, which was shortened to "commander" in 1794. When he was in command of a ship, such as a sloop or brig, a master commandant would be addressed as "captain" by the sailors on board.