NITED STATES NAVY DEPARTMENT,
Washington, February 18, 1846
It having been represented to the Department, that confusion arises from the use of the words "Larboard" and "Starboard," in consequence of the similiarity of sound, the word "Port" is hereafter to be substituted for "Larboard."
GEORGE BANCROFT."
Source; -DEPARTMENT OF THE NAVY -- NAVAL HISTORICAL CENTER 805 KIDDER BREESE SE -- WASHINGTON NAVY YARD WASHINGTON DC 20374-5060
Read more: Answers.com - What is the history of port and starboard running lights and why were these colors used

