Cooley arrived in East Florida in 1813, during a joint campaign of Tennessee and Georgia forces. Some sources give credit to the hypothesis that Cooley fought with the Tennessee Volunteers under Colonel John Williams; other sources say he was a lieutenant in the Georgia Militia, fighting under Colonel Samuel Alexander from Georgia. Cooley acquired property in Girt's Landing on the St. Marys River, close to where the military units crossed East Florida that same year. Later, he went to the west bank of the St. Johns River, settling in an area south of modern Jacksonville.