Didn't the ICBM development come first? The Mercury and Gemini programs used barely modified ICBM boosters and the engineers at first didn't want to put contro

Didn't the ICBM development come first? The Mercury and Gemini programs used barely modified ICBM boosters and the engineers at first didn't want to put controls in at all, they were already confident of their ability to maneuver and navigate in orbit. At some point I think the simplest explanation is the correct one - it was a giant contest of wills between the superpowers.