Louis rose through the ranks to major while on MIA status. He was sent to Vietnam for a tour of duty. He flew counter insurgency missions as a navigator in an A-26A Invader aircraft, converted from a World War II B-26 – a fast twin-engine bomber. On April 28, 1968, Major Louis Fulda Guillermin was Missing In Action on a mission over Savannakhet Province, Laos. His last known position was about 10 miles east of the city of Ban Muong Sen. This was his second tour in South East Asia.

Louis rose through the ranks to major while on MIA status. He was sent to Vietnam for a tour of duty. He flew counter insurgency missions as a navigator in an A-26A Invader aircraft, converted from a World War II B-26 – a fast twin-engine bomber. On April 28, 1968, Major Louis Fulda Guillermin was Missing In Action on a mission over Savannakhet Province, Laos. His last known position was about 10 miles east of the city of Ban Muong Sen. This was his second tour in South East Asia.