People doubted the meetings would succeed. The leaders had different personalities. The countries had been fighting for decades. Even Begin didn't expect an agreement, insisting the meeting focused on scheduling future summits. Sadat, however, was willing to negotiate controversial topics.
The 13-day summit began on September 5th, 1978. They worked privately in Carter's cabin. Carter insisted on no press coverage, as it may hinder negotiations. After three days, direct discussion between Sadat and Begin was impossible. Carter created a document, then asked the leaders for comments and revisions. It was revised around two dozen times. As time passed, an agreement seemed unlikely. Sadat threatened to leave, and Carter planned a return to the White House. On the final day, they reached an agreement. Begin allowed the Knesset to decide on Sinai. They gave it back to Egypt.
"Israeli Prime Minister Menachem Begin, Egyptian President Anwar Sadat and U.S. President Jimmy Carter at Camp David" (United States Institute of Peace)