On the 28th of February, 1893, William was born in Boston, Massachusetts, to William and Abigail. They moved to Garden City, New York where he grew up with his half-brother, Charles, and attended St. Paul’s School before transferring to Trinity-Pawling School. After high school, William attended Williams College in Williamstown, Massachusetts, where he played football, basketball, and baseball, graduating in 1914. After college, he enlisted in the New York National Guard and was mobilized to the Texas-Mexico border from July to December of 1916. William accepted a commission to Second Lieutenant shortly before the 12th New York Cavalry deployed to France. The 12th New York Cavalry was redesignated the 105th Infantry Regiment and William was a First Lieutenant when his actions would earn him the Medal of Honor. The citation reads:

He led a small group of men to the attack, under terrific artillery and machine-gun fire, after they had become separated from the rest of the company in the darkness. Singlehandedly he rushed an enemy machine gun which had suddenly opened fire on his group and killed the crew with his pistol. He then pressed forward to another machine-gun post 25 yards away and had killed one gunner himself by the time the remainder of his detachment arrived and put the gun out of action. With the utmost bravery he continued to lead his men over three lines of hostile trenches, cleaning up each one as they advanced, regardless of the fact that he had been wounded three times, and killed several of the enemy in hand-to-hand encounters. After his pistol ammunition was exhausted, this gallant officer seized the rifle of a dead soldier, bayoneted several members of a machine-gun crew, and shot the other. Upon reaching the fourth-line trench, which was his objective, 1st Lt. Turner captured it with the nine men remaining in his group and resisted a hostile counterattack until he was finally surrounded and killed.

William Bradford Turner was 26 years old when he died and the Medal of Honor was posthumously awarded to him on the 26th of June, 1919. He is buried in the Somme American Cemetery and Memorial in Bony, France (Plot B, Row 13, Grave 1) and his name is listed on the memorial where his father and brother are buried in the South Burial Ground in Warren, Rhode Island.