Back when I was a wee Heathen in the 1970s, World War II wasn’t ancient history. Nazis were still pretty reliable go-to villains, even 30 years after their surrender (e.g.).
Rarer but still somewhat common was the trope of the “isolated Japanese soldier, lost on an island or in the wilderness, who still believes the war is on.” I saw this more than a few times — I remember an episode of Gilligan’s Island originally broadcast in 1965, but also one from the Six Million Dollar Man in 1975, and another from the 1979 show Salvage 1.
The reason this trop was so popular is simple: it was grounded in the real. Holdouts were discovered as late as 1974, nearly 30 years after the end of the war.
One of the last of those men, Lt. Hiroo Onoda, famously refused to believe the war was over until his former commander flew there from Japan to issue orders personally.