Williams was born on August 25, 1897, in Denton, Texas. He attended the schools of Denton, and graduated from Denton High School in 1916. In May 1916, he enlisted as a private in the Texas Army National Guard. He took part in the expedition against Pancho Villa, advancing to corporal and sergeant in 1917. Having claimed an 1896 date of birth in order to meet the minimum age for a commission, In May 1917 Williams began the officers training course at Camp Bullis, Leon Springs, Texas. He received his commission in August 1917, four months after the American entry into World War I, and was appointed a second lieutenant in the Infantry Branch of the Officer Reserve Corps.