While the U.S. Navy is older than the Marine Corps, the Marine Corps takes precedence due to previous inconsistencies in the Navy's birth date. The Marine Corps has recognized its observed birth date on a more consistent basis. The Second Continental Congress is considered to have established the Navy on 13 October 1775 by authorizing the purchase of ships, but did not actually pass the "Rules for the Regulation of the Navy of the United Colonies" until 27 November 1775. The Marine Corps was established by an act of the Second Continental Congress on 10 November 1775. The Navy did not officially recognize 13 October 1775 as its birth date until 1972, when then–chief of naval operations Admiral Elmo Zumwalt authorized it to be observed as such.