On August 22, 1814, explosions erupted on the Patuxent when the U.S. Chesapeake Flotilla scuttled its own vessels as British pursuers approached. With the flotilla destroyed, the British landed about 500 troops at Mount Calvert and marched from there to Upper Marlboro to join the main British invasion force. British Rear Adm. George Cockburn sent orders for Marines and naval forces at Pig Point to move at once to Mount Calvert and with the utmost expedition join the army, which he agreed to accompany. Anchored off Mount Calvert, Cockburn reported the complete destruction of the enemy flotilla and then set out to join the assault on Washington, D.C., while Joshua Barney and 400 American flotillamen rushed to help defend the capital.