In the late summer of 1864, a Union combined Army-Navy force began operations to close Mobile Bay to blockade-running vessels from the port city of Mobile, Alabama. On August 3, infantry and cavalrymen under Maj. Gen. Gordon Granger landed on Dauphin Island and laid siege to Fort Gaines west of the main ship channel. Two days later, Rear Admiral David G. Farragut’s fleet of eighteen ships, including four ironclad monitors, entered Mobile Bay and received devastating fire from both Fort Gaines and Fort Morgan, east of the channel. Farragut's fleet successfully navigated the narrow, torpedo-filled passage, losing only the ironclad USS Tecumseh. After passing both forts, Farragut engaged a Confederate naval force inside the harbor under Adm. Franklin Buchanan, including the ironclad ram CSS Tennessee, and forced it to surrender. Without naval support, the garrisons of both forts were vulnerable and were forced to capitulate. The loss of the Confederate fleet and forts shut down the port, although the city of Mobile would not surrender until April, 1865.