The Crusades
1100s - First Crusade (1096-1099) - Second Crusade (1145-1149) - Third Crusade (1189-1192) - Fourth Crusade (1202-1204)
1096-1099 - Pope Urban II calls (aid Byzantine - Alexios I Komnenus against Seljuks) - Gather in Constantinople - Siege of Jerusalem - Four Crusader States (Jerusalem, Edessa, Antioch, Tripoli)
1145-1149 - First fall of a Crusader state (Edessa) - Responding to Pope's call, Louis VII of France and Conrad III of Germany march separately and are each defeated by the Seljuks
1189-1192 - Fall of Jerusalem to Saladin in 1187 - Three Kings - Richard I (England), Philip II (France), Frederick Barbarossa (Holy Roman) - Treaty of Jaffa (Muslims keep Jerusalem, but Christian pilgrims and merchants allowed)
1202-1204 - Ostensibly aiming to take Jerusalem - Sack of Constantinople and Partition of the Byzantine Empire