Hood's men retreated to Devil's Den. This rocky area was at the foot of Little Round Top. At this point, the Union troops didn't occupy Little Round Top. However, General Gouverneur K. Warren of the Union , spotted the Confederates in Devil's Den and called for reinforcements. Colonel Strong Vincent disobeyed orders and took his brigade to defend Little Round Top. Fifteen minutes after Vincent arrived, the Confederates ran up the southeastern edge of the hill. The 385 men of the Twentieth Maine Regiment under Colonel Joshua L. Chamberlain, fought with 500 soldiers of Colonel William C. Oats's Fifteenth Alabama Regiment. A Texas regiment came to help the Alabama Corp. The South started to gain ground. However, Oats and his men were driven off Little Round Top after an hour of hard fighting. The Union used 20,000 rounds of ammunition. The Twentieth Maine had so few bullets left that it had to finish the battle with a bayonet charge. They lost a third of their men. The Fifteenth Maine lost almost half.