Yep. This date is actually the "reactivation" of the Marine Corps. Most of us never knew there was a "deactivation", and I never knew a Marine who acknowledged it. The traditional belief in the founding of the Marine Corps, is that it took place at Tun Tavern in Philadelphia on November 10, 1775 ... before there was even a Navy ... thus the Marine assertion that they are the "senior" Naval Service.
In any event, Semper Fi, and Happy reactivation Birthday, fellow Marines!