President Kennedy proposed the manned lunar landing as the focus of the US space program but, at the time of his address, only one American, Alan B. Shepard, Jr. had been into space, on a suborbital lob shot lasting 15 minutes. No rocket launch vehicle was available for a lunar voyage and there was no agreed upon method for placing any kind of spacecraft safely on the lunar surface and getting it back to the earth. Nor was there agreement within NASA itself on how it should be done.
This brings us to Project Gemini. Gemini started after Apollo had begun, in part to answer a crucial question for Apollo. Was rendezvous and docking in orbit a feasible basis for a manned lunar landing mission?