Philip Robson Locke was born and raised in Waynesburg, Pennsylvania. His father, William Locke, was a coal miner. His mother, Cissie Locke, was a maid. After Locke graduated from high school, he went on to Princeton University on an Army Reserve Officers' Training Corps scholarship. He graduated from Princeton with a Bachelor of Arts in Mathematics and a commission as a Second Lieutenant in the United States Army via ROTC. Soon after, Locke married his girlfriend of three years, Rose. While at Princeton, he decided to become an infantry officer.