I couldn't find a fort, so you're going to have to use your imagination for this one.
Battle of Shiloh
Battle of Palmito Ranch
Confederate soldiers started off the civil war when they fired shots at Fort Sumter. Because of how unprepared the Union was, the Confederate army quickly won this battle.
The battle of Shiloh was a battle lasting 2 days in Tennessee where the Confederates surprised attacked Union soldiers waiting for reinforcements. On the first day of the battle, the Confederates were winning, but the Union fought back and won.
The battle of Palmito Ranch occurred on May 12-13, 1863, when the Union Colonel Barrett desired "a little battlefield glory before the war ended altogether" - Barrett's detractors