U.S. Navy petty officers first class, selected for promotion to chief petty officer, climb the shrouds on the mizzen mast aboard USS Constitution during Chief Petty Officer Heritage Weeks. During the week, Constitution Sailors teach petty officers first class, selected for promotion to chief petty officer, a variety of time-honored maritime evolutions while living and working aboard the ship. USS Constitution is the world's oldest commissioned warship afloat and played a crucial role in the Barbary Wars and the War of 1812, actively defending sea lanes from 1797 to 1855. During normal operations, the active-duty Sailors stationed aboard USS Constitution provide free tours and offer public visitation to more than 600,000 people a year as they support the ship's mission of promoting the Navy's history and maritime heritage and raising awareness of the importance of a sustained naval presence. USS Constitution was undefeated in battle and destroyed or captured 33 opponents. The ship earned the nickname of Old Ironsides during the War of 1812 when British cannonballs were seen bouncing off the ship's wooden hull. (U.S. Navy photo by Mass Communication Specialist 2nd Class Amber Speer)