Queen Elizabeth 2 must have set many records in longevity. One of them was being the last surviving Head of State who saw service in World War 2:
https://www.autoweek.com/news/people/a41123474/remembering-queen-elizabeth-ii-wwii-mechanic/
Before her, the last surviving head of state who served in WW2 was George HW Bush (1924-2018). He served as a carrier pilot in the US Navy and saw active service, being shot down off the Bonin Islands off Japan.
He was the only survivor of a mission in which several of his comrades died in gruesome circumstances:
https://en.wikipedia.org/wiki/George_H._W._Bush#World_War_II
More details here about the Japanese atrocities:
https://en.wikipedia.org/wiki/Chichijima_incident
Tail piece: Can you think of any prominent Indian political leader in recent times who had seen any significant military service?