The Crusades were a series of religious wars between Christians and Muslims originally to secure control of holy sites.
OUR CASTLE NOW!
Sir, where do you want us to attack? We've been losing fights in Edessa, but you've asked us to protect everywhere!
In 1147, the Muslims captured the city of Edessa, which was part of the Holy Land, and was created by the Crusaders. Pope Eugenius III wanted to create the 2nd crusade, but did not set a clear goal - instead asked to protect all of the area that was captured in the first crusade. This would later become a problem, as there was no objective to aim for.
In the period between 1187 and 1192, Saladin the sultan of Egypt reclaimed Jerusalem, and the Crusaders launched efforts to reclaim the city with force, but were not able to and were only granted the right for pilgrims to visit the city.
Finally, we have reclaimed the Holy Land!
Look guys, there is more gold here! We're all going to be rich!
The 4th Crusade, from 1202 - 1204. The Crusaders launched more effort than ever to reclaim the Holy Land. The objective was obviously Jerusalem, but greed overcame the soldiers, so they decided to invade Constantinople, since it had lots of property.
In 1212, children were sent to Jerusalem because people thought that children would be able to get Jerusalem back, as they were known to be dedicated to their religion. At the end they were sold as slaves, this was the Fifth Crusade and it was a failure!
Lets go take back Jerusalem!
We're not doing anything!
Crusades 5 to 9 occurred during 1217 to 1272. None of these crusades would do much, But at the start of 1270 Louis IX left for Tunis, however he ended up dying there before he even started fighting and eventually the Crusaders learnt their lesson and that tragic event ended the era of the Crusades.