William Louis Ahrens was born on 30 December 1917 to Gertrude and William Ahrens in an apartment in St. Louis’ Dutchtown neighborhood near Michigan Avenue and South Broadway. The Ahrens spoke German in the household in William’s youth. The family moved to 3737 Blow Street in the Carondelet neighborhood. William worked for his father's business Ahrens Coffee, Tea and Spice Company and graduated from Cleveland High School in 1935. He later worked at the International Shoe Company from November 1939 to February 1941.

Ahrens was inducted into the U.S. Army on 24 February 1941 at Jefferson Barracks. He served with the 138th Infantry, 7th Division for three years as an instrument observer in the Aleutian Islands. When he returned to the United States, Ahrens earned the rank of platoon sergeant and was responsible for training in military tactics and weapons at Fort McClellan. He earned the American Defense Service Medal, the Asiatic-Pacific Theatre Service Medal with one bronze star, and the Good Conduct Medal.

After the war Ahrens was employed by the Aeronautical Chart and Information Center located at the former St. Louis Arsenal. He married Flora Ruth Dendy (1925-2018) and the couple had one daughter, Donna R. Ahrens. William Ahrens died on 12 June 1997 and was interred at Jefferson Barrack National Cemetery.