In December 1941, he enlisted in the United States Navy and was commissioned an officer in 1942, rising to the rank of lieutenant.

He served on anti-submarine duty and on a combat minesweeper in the North African and Mediterranean theatres, having participated in the assault on Italy.

Returning to Birmingham after the war, Seibels co-chaired the committee responsible for the safety torch on the Vulcan statue.

After a single term on the City Council he was elected mayor in 1967, succeeding the retiring Albert Boutwell, who himself had defeated the notorious "Bull" Connor four years earlier.

He retired from elective public office in 1990 but remained active in party politics where he was affectionately known as "Mr. Republican" among Alabama GOPers.