Leonard Lavern Koebel was born on July 14, 1917, the son of Charles Oswald Koebel and Olivia Barbara Koebel. He served in the 401st Bomber Squadron, 91st Bomber Group, Heavy, as a Second Lieutenant during World War II. 2LT Koebel was the Bombardier on B-17F Flying Fortress #41-24451 that crashed in Mount Slieveanorra, near Cushendall, Northern Ireland while in transit to Great Britain due to bad weather. Eight of the ten on board were killed, including 2LT Koebel, while two survived.

Killed aboard were:
1st Lt. John A. McLean, Pilot
2nd Lt. Leonard L. Koebel, Bombardier
Capt. Dale L. Lasselle - Co-Pilot
Capt. George C. Wassell - passenger
Sgt. Robert J. Vaughan - Gunner
Cpl. John N. Gibson - Radio operator
Pvt. Justin C. Hamblin - Engineer

Survivors:
Corp. Leon Harrison - Flight Engineer
PFC Norman E. Wicks - Radio Operator

2LT Koebel is buried now in the Greenwood Memorial Park, San Diego, San Diego County, California, USA.