He wanted to join the New York City Fire Department when he read about Samuel Jesse Battle joining the New York City police department. The first African-American to join the New York City Fire Department was William H. Nicholson, who joined in 1898. Williams had a very high score on his written test. He scored perfect on his physical examination. All firefighter candidates must have a character reference. His was written by former U.S. president Theodore Roosevelt. Even so he was put on the waiting list while others were hired ahead of him. Williams finally joined on January 10, 1919. He was assigned to Engine Company 55 in Manhattan, New York City. Williams was promoted to lieutenant in 1927.