One of the greatest things that the Papal States could do in the Middle Ages was declare ‘Holy War’ or a Crusade, on a specific nation, target, or group of people. This allowed for a period of relative peace within Europe as various Christian kings took up the sword and moved to defend their faith against pagans, heretics, and expanding hordes.
We all know of the 1st-5th crusades for Jerusalem, where the armies of Christendom marched to aid the Byzantine Empire and regain the Holy Land. Robin Hood, the Knights Templar, and the failure of the 4th crusade come to mind.
However, not many people know of Crusades that moved to battle other targets, such as the scourge of Europe – the Ottomans.
The Ottoman expansion
Once the final Crusade to hold Jerusalem failed, the Ottomans charged in and took over the remains of the Byzantine Empire and began to rapidly grow their empire in size. Before beginning to threaten Hungary with boasts that they would cut through Hungary and Italy.
Seeking aid, Hungary requested aid from other European powers, and an army of Crusaders marched down to lay siege to a Turkish city before being defeated in Bulgaria. After several more battles and an ineffective peace treaty failed to halt the Ottoman expansion into Europe, the crusade was called.
The Crusade of Varna
Pope Eugene the IV called for the Crusade when civil wars in both Hungary and Byzantium came to an end, and after a large Ottoman army was defeated by a Hungary leader, he sent out a decree to launch a crusade on the Ottomans, incorrectly believing they were weak and would be easily destroyed by a concentrated force.
The armies of Hungary, Poland, Transylvania, and Burgundy led the force, alongside the Teutonic Knights, Lithuania, and Bohemia. After capturing several towns, the Crusaders fought a battle in the snow against a prepared Ottoman force at Zlatitsa. They were defeated but soon ambushed a force that was sent to chase them down.
A treaty between the warring forces was soon signed, but it ironically allowed for the Crusaders to keep fighting the Ottomans, so it was largely a formality. The Papal States, as well as the Crusaders, wished to keep pressing their attack, and so they simply ignored it.
Battle of Varna and the Aftermath
The Crusader forces pushed deeper into Ottoman territory and were soon caught by a 50,000 strong Ottoman army at Varna. They were unable to retreat and instead took up defensive positions near the water and the wood covered hills.
Despite knocking the Ottomans back with heavy losses due to having firearms and stronger positions, the Christians abandoned these positions to pursue their foes and were slaughtered by reinforcements. The Polish king was slain and the Crusader forces retreated, losing many men along the way.
This defeat destabilized Europe and more importantly, made every king think twice about opposing the Ottomans, effectively allowing them to continue their expansion through Europe.