There's a great movie called "Best of Enemies" about their rivalry and the impact of their televised debates. It's on Netflix. It's a 94% on Rotten Tomatoes. Definitely worth watching.
They neglect to mention that when Mailer decked Vidal (I think calling it a fight is an exaggeration), Vidal, still on the floor, is reported to have retorted: “Words fail Norman Mailer yet again.”.
They do manage to keep his commentary on Capote's death ("A good career move").
Was a horrible thing to say, but the context is rarely fully explained. Vidal called him a "nazi" first.
He served in the U.S. Army in WWII and was a member of Franklin Roosevelt's honor guard...so that probably was a pretty "deep cut" as an insult for someone with his military background.
Again doesn't make it right, but probably safe to say for him it was not the same as calling someone that from r/The_Donald in 2018.
Buckley did serve in the army during WWII, as did Vidal. Both of them served stateside and never saw any action.
During the debate, after the infamous “queer” remark, Buckley said that he “served in the infantry during WWII,” implying that he had fought in battle, which he never had.
He is not a Nazi because he fought against them, but someone who had the same views as him today simply would be labelled a Nazi (or at least Nazi sympathizer) by many in the current environment. Strange times.