Fort George, originally known by its garrison as Fort Penobscot and called Fort Castine by Admiral Sir George Collier in his reports, received its present name from its builder, British general Francis McLean, when it was completed in December 1779. Begun in June, it was unsuccessfully besieged from July 29 to August 13 by combined American land and naval forces during the Penobscot Expedition, the largest American naval expedition of the Revolutionary War. After learning that the British were establishing the fort, authorities in Boston sent a squadron of nineteen warships under Commodore Dudley Saltonstall and twenty-four transports carrying 1,200 men under General Solomon Lovell to destroy the fort and its garrison. When the Americans reached Penobscot Bay on July 25, three British Royal Navy sloops were nearby in the bay. After landing his troops, Lovell decided that taking the fort by land was too risky because the British ships could bombard them during an attack, and although he repeatedly urged Saltonstall to attack those ships, Saltonstall refused despite having more ships and more guns. On August 13, a British relief force of six warships, including a 64-gun ship of the line and four frigates, arrived to aid the garrison. Though the Americans still outgunned the British, Saltonstall ordered his ships to flee up the Penobscot River and then burned them, forcing the soldiers who had taken part in the assault to make their way back to Boston on foot through the wilderness. Saltonstall was removed from the service for his actions, and Paul Revere, who had charge of artillery for the expedition, was acquitted in a court-martial though his reputation was permanently damaged. The fort was the last post surrendered by the British at the close of the Revolutionary War, and as they departed in 1784 they burned the buildings within it. British forces occupied it again in September 1814, rebuilt it, and mounted sixty cannon there. When those troops destroyed and evacuated it in April 1815, American troops rebuilt and strengthened it again and occupied it until March 1819, when it was permanently abandoned as a military post. The Penobscot Expedition remained the worst defeat in U.S. Navy history until the attack on Pearl Harbor in 1941.