William Henry McWhirter was born on August 26, 1918, in Linesville, Crawford County, Pennsylvania. He had one year of high school, had a civil occupation as semiskilled in foundry occupations, and was single without dependents upon enlistment. He entered military service at Camp Perry Lacarne, Ohio, on February 12, 1942.

William served in the HQ Company of the 2nd Ranger Battalion as a Private First Class during World War II. He was Killed in Action on June 6, 1944, at the age of 25, in Vierville-sur-Mer, during the American assault on Omaha and Utah beaches in France. PFC McWhirter is now buried in the Normandy American Cemetery, Colleville-Sur-Mer, France. His name is commemorated on the Rangers Memorial Plaque at Pointe du Hoc, Cricqueville-en-Bessin, France, but his middle initial is inscribed as P.