The son of August Florino and Mable Thomas (Thayer) Iaccaci, Paul Thayer Iaccaci attended Harvard from 1909 to 1911. He and his brother August enlisted in a New York city regiment in June 1913 and served on the Mexican border in 1916. In 1917, they both joined the Royal Flying Corps in Toronto, Canada. Arriving in England, they completed their training at Netheravon and received commissions. In April 1918 the Iaccaci brothers were both posted to Calais where they flew Bristol Fighters with 20 Squadron. Each of them was credited with 17 victories while serving with this squadron. Lieutenant Paul Iaccaci was transferred to the unemployed list on 1 April 1919. He and his brother returned home to the United States.
Appears as Paul Thayer Jaccaci in some documents.
Harvard´s Military Record in the World War
Harvard College, Class of 1913, Secretary's second report, June 1917
Distinguished Flying Cross (DFC)
"Lieut. Paul Thayer Iaccaci.
A bold and successful fighter, who on four offensive patrols has accounted for six enemy aeroplanes: two he shot down himself, and four were destroyed with the assistance of his observer. In these several encounters the formation in which, Lieut. laccaci was serving was engaged against heavy odds."