Today is the Birthday for the United States Navy!
The navy has been around since 1775. It was the 3rd branch of the military established. The National Guard and the U.S. Army were established before the U.S. Navy.
Here is a list of the other Military Birthdays:
National Guard: December 16, 1636
U.S. Army: June 14, 1775
U.S. Navy: October 13, 1775
U.S. Marine Corps: November 10, 1775
U.S. Coast Guard: August 4, 1790
U.S. Air Force: September 18, 1947