At the Battle of Belmont, Missouri, in 1861, Union General Ulysses S. Grant landed his troops on the Missouri shore and advanced toward Belmont, where Federal forces fought through woods and a cornfield against a Confederate line that was weakened by low ammunition and broken after repeated fighting. Confederate troops fell back behind the defenses of Camp Johnson, where Union forces, aided by artillery and the gunboats USS Tyler and USS Lexington, pressed the attack until the camp was entered and the Confederate second line collapsed. As Confederate soldiers retreated upriver, Union troops pursued them, then returned to Camp Johnson, where celebration, looting, and the burning of the camp followed; some wounded and sick Confederates were burned in their tents, leading later to Confederate claims that Northern troops had murdered Southern soldiers there. Confederate reinforcements then arrived by steamer, including troops organized by Brigadier General Frank Cheatham, and Grant, seeing the danger, reorganized his men and began a retreat to the transports, but his column was attacked at both rear and front before Federal artillery opened a path through the Confederate line and the troops reached their boats. Additional Confederate reinforcements under Polk then moved on the landing and fired on the Federals as they boarded, after which the Federal gunboats fired on the Confederates and Grant's transports steamed upriver toward Cairo, Illinois. Though both sides claimed victory, the battle was not a clear victory for either side and had no military significance, but it was important as Grant's first major battle, as the beginning of his Civil War career, and as the opening of the Federal campaign to win the Mississippi River; it also left both armies with battle-tried soldiers, and afterward officers from both sides met under flags of truce to exchange prisoners and later made social calls. In 1862, after Grant defeated the Confederates at Forts Donelson and Henry, Columbus was left vulnerable, and Polk withdrew after destroying buildings and supplies, allowing Federal forces to enter without firing a shot.