Just finished “The Great Betrayal” by Ernle Bradford on audio. it’s a history of the 4th Crusade. In 1204, the Crusaders (mostly French) hire Venice and their ships to take them to the Middle East (Egypt or Syria..either one is ok with them). The Doge of Venice, Dandolo, who has a secret alliance with Egypt, and maybe a personal score to settle, takes the Crusaders to Constantinople instead (Istanbul today), perhaps the world’s greatest city at the time and the capitol of the Byzantine empire and the Eastern Christian church. The Crusaders breach their impassable walls, destroy much of the city, steal much of its extraordinary treasure (now in Churches all over Europe, esp. Venice), and dethrone their emperor..
The result is a dramatically weakened Eastern Christian church/empire. Constantinople officially falls to the Muslim Turks 200 years later but there’s little left to conquer at that point. The net result of the 4th Crusade is the dramatic advance of the Ottoman Empire into a weakened, leaderless Eastern Europe and really explains that part of the world for the next 700 years.
Sir Steven Runciman
, medieval historian, wrote in 1954: "There was never a greater crime against humanity than the Fourth Crusade."
Before reading this, I had no idea. I didn’t know the role that the West had in advancing Islam into that city and westward, I thought they did it all on their own.