The Crusades were during the medieval ages. There were nine numerical crusades, and two non-numerical crusades. The Crusades lasted over about 200 years (from 1095 to 1291).
This is the region where most of the fighting happened.
This is picture of a battle taking place during the Second Crusades, based off of the book Histoire d'Outremer, by William of Tyre. William of Tyre lived through the first and second crusades.
Peter the Hermit preached to people about the first crusades; he supported it. He is a significant figure of the first crusades because he had a big following, and people believed in his words.
Alexius I was a Byzantine Emperor that helped the Crusaders ban together to defeat the Turks. By defeating the Turks, Alexius made an alliance with the Crusaders, which helped his empire grow.
The pope at the time (Eugene III) ordered there to be a second crusade. Bernard of Clarivaux was ordered to convince the people to fight for the Holy Land. Bernard of Clairvaux acted as the modern day media.
Saladin was a Muslim general who recaptured the Holy Land and defeated the Crusaders in many battles. Some of these battles took place in Egypt and Mediterranean Sea. He was involved during the third crusades.
This crusade is a bit of a misnomer because the "children" were actually people that were marching for the cause of the crusades. They didn't really have to be children to be involved.
Pope Innocent III was involved in the Fourth, Fifth and Albigensian crusades, which ranged from 1202 to 1221.