Complex sentence: Although the Third Crusade, in the end, failed to retake Jerusalem, a three year truce, the Treaty of Jaffa, was eventually negotiated with Saladin-Christian pilgrims from the west would once again be allowed to visit Jerusalem.
Split into simpler sentences: Although the Third Crusade, in the end, failed to retake Jerusalem, a three year truce was eventually negotiated with Saladin. The truce, known as the Treaty of Jaffa, ensured that Christian pilgrims from the west would once again be allowed to visit Jerusalem.