Mr Collier was born a slave in the state of Mississippi. At age 10, he had killed his first bear, as it was his job to supply meat for his master's family. When the Civil War broke out, Collier was eager to fight, but his master told him he was too young, stating "I begged like a dog, but they stuck to it -- 'You are too young'". Despite this, he stowed away on a riverboat and joined his master's son in Memphis, Tennessee.
He was present at the Battle of Shiloh and witnessed the death of General Johnston and, despite there being a prohibition against blacks serving in uniform, the Confederate army made an exception due to Collier's impressive skills. Collier would serve throughout the war, fighting in Alabama, Tennessee, and Mississippi.
At the end of the war, he was connected to the killing of a Yankee soldier during the Northern occupation and was arrested, but thanks to the persistent efforts of Colonel W. A. Percy, he was not executed. He partook in several protests against the occupation and said he was "the only negro among 500 white men" marching up Washington Avenue under fire, as a protest against the insults to the white men and women of Greenville.