Threats to Christian security very much increased with the Ottoman victory over Byzantium. Dr. John Rao describes the Ottoman advance, which continued, seemingly unabated, into Africa and southeastern Europe, causing Venice, Austria, and Spain to think that a conscious, dangerous pincer movement was in operation. Many critical moments awaited the Christian world until the Poles, Austrians, and Russians turned the tide against the Turks in the 1700's. Taken from: Crusading, the Crusader & the Christian Order - 2002 VonHildebrand Institute