After Apollo 1, the Apollo program was put on hold while the accident could be investigated. How long was the program put on hold? How much did it delay the actual Moon landing?
The delay was not only the hold for investigation. More time was needed to design and build a new hatch, to develop a fire proof cloth for the space suits outer layer, to modify the suits and to remove all flammable material from the Command Module and replace it with fire proof material.
Apollo 4 was delayed for about a year:
"Originally planned for late 1966, the flight was delayed to November 9, 1967"
$\begingroup$ "Originally planned for late 1966" So Apollo 4 was already behind schedule when Apollo 1 occurred (Jan 27 1967)? $\endgroup$– DJohnMJul 18, 2021 at 19:58
$\begingroup$ @DJohnM The last Gemini 12 flight was 15. November 1966. The first successful docking was Gemini 10 at 18. Jul. 1966, they did three dockings with Gemini 10, 11 and 12. The first docking of Apollo CM to LM should be tried not before the last Gemini flight. $\endgroup$– UweJul 19, 2021 at 0:50