Delon was actually a military veteran.
Delon joined the French navy at age 17 and was sent to Indochina.
Hw wasn’t a very honorable veteran. According to this obituary in today’s Telegraph:
“After applying unsuccessfully to be a test pilot, he joined the French navy, reporting to Brest in 1953. Already known to police in connection with petty offences, he left for Indochina as a wireless operator. He was discharged after stealing a military jeep and spent his 20th birthday in prison. On his return to France, he served a further 45 days near Toulon for stealing a gun in Saigon.”