There was a period of time - in the late ‘50s and early ‘60s, I believe - during which accepted Air Force doctrine and policy was that there would be no more dogfights. That dogfights couldn’t happen anymore because closing speeds and angular rates were so high that human reaction times wouldn’t be able to deal with a dogfight.
Air Force thinking was - for a time - that everything would depend on air-to-air missiles and other stand-off capabilities.
Perhaps the lack of guns on the Phantom was a result of this policy.
That’s about it.
A cannon was added once that doctrine was abandoned.
I think that is exactly what led to that thinking; I guess hindsight is 20/20. I’ve seen interviews with pilots from Vietnam describing how it nearly cost them their lives.
But the F4 was originally built for the navy.
First time I saw an F4H was at MCAS Beaufort. We were working a rare Saturday (F8U-2NE squadron), so everyone was working off a hangover. Two F4H planes took off and immediately hit afterburners. Three guys fell on the ground holding their head, screaming.