On board the U.S.S. Florida, Sinnett showed extraordinary heroism in the line of his profession during the seizure of Vera Cruz, Mexico, 21 April 1914.
Presented by Secretary of the Navy Josephus Daniels on the deck of the USS Florida at the Brooklyn Navy Yard, Brooklyn, New York.
Additional information on his action comes from U.S. Navy General Order No. 101, dated June 15, 1914. "On April 21, at about 12:30 p.m., Ensign G. M. Lowry, in command of First Company, Florida Battalion, at the customhouse, called for volunteers to go into an alleyway betwen the customhouse and an open warehouse down which a heavy fire was being directed by the enemy. Sinnett responded with four others and finally succeeded in dislodging the enemy." The other four volunteers were George Cregan, Harry C. Beasley, Joseph G. Harner, and J. F. Schumacker. All except for Schumacker received the Medal of Honor.