Excerpts from Books and Wikipedia
"In the winter of 1229, the maverick emperor succeeded where previous crusaders had repeatedly failed: he reclaimed control of Jerusalem, captured from the Christians more than four decades before by the celebrated Muslim warrior Saladin. . . . Instead, Frederick painstakingly negotiated the peaceful handover of Jerusalem and surrounding territory with Sultan al-Kamil, who then controlled the Holy Land." [Lyons: House of Wisdom, p. 166-7] "Al-Kamil handed it over to Frederick with a slew of conditions: he was not to rebuild the walls, the nearby villages would remain Muslim, the Temple Mount (including the Dome of the Rock) was to stay in Muslim hands, with the Christians only given visiting rights, and Muslim worship was to continue there uninterrupted. Without striking a blow, Frederick had attained the goal of all of the Crusades since 1100 . . ." [Bauer: Renaissance World, Kindle Edition, Location 5017-29]