Crusades

The First Crusades began during the Middle Ages in the year 1095 as the result of a cry for help against invading Islamic armies.
460 years after the first Christian city was overrun by Muslim armies.
457 years before Jerusalem was conquered by Muslim armies
453 years after Egypt was taken from Christendom by Muslim armies
443 years after Muslim armies invaded and plundered Italy
427 years after Muslim armies first laid siege to Christendom's Eastern Capital of Constantinople.
380 years after Spain was conquered by Muslim armies
363 years after France was first invaded by Muslim armies
249 years after Rome itself was attacked by Muslim armies

This was only AFTER four centuries of church burnings, killings, enslavement and forced conversions of Christians.
By the time the Crusades began 2/3 of the Christian world had been conquered and its people forced to convert or be enslaved to Islam.

Without Charles Martel, the Battle of Tours in 732; The Templar Knights 1129 -1312; El Cid's reconquest in 1085: the Venetian fleet at La Ponto 1571; the Polish and Austrian knights at the Gates of Vienna in 1683; the Serbian Hajduks fighting off the Ottoman Turks 1804, Europe might have been converted to Islam.