Crusaders, Mamelukes, and Turks: The Crusaders established a feudal Christian state with Godfrey at its head. They built many impressive churches during the term of the first Latin Kingdom of Jerusalem, but in 1187 they were driven out by Muslim forces under the great warrior Saladin. During the Sixth Crusade (1228– 1229), the Holy Roman Emperor Frederick II managed to secure Jerusalem for the Christians by negotiation. The Christians, however, could not hold the city. After they lost Jerusalem, a Mongol invasion swept through, and in 1244 the Mameluke dynasty of Egypt took control, ruling Jerusalem for the next 250 years. The city struggled to rebuild from Crusader wars and invasions. Much of the best Islamic architecture in the city was constructed in the Mameluke era, but the past thousand years had taken their toll: Jerusalem was unable to regain the prosperity it had enjoyed in earlier times. In the early 16th century, the Ottoman Turkish Empire was advancing through the Middle East. Jerusalem fell to the Ottomans in 1517, remaining under their control for 400 years. Suleiman the Magnificent rebuilt the walls and gates in the form they retain to this day. Fountains, inns, religious schools, and barracks were constructed. But when Suleiman died, his empire, including Jerusalem, began a long period of decline. The Holy City remained a backwater until the 19th century, when renewed interest among Christian pilgrims made it the destination of thousands of travelers each year. 
What happened during the Sixth Crusade with the Christians?
Christians gained control of Jerusalem