The unit can only be recruited by the AI and more to the point, the AI can recruit more than one of this unit so do please be careful before you decide to go to war against either of the crusader kingdoms. If you do lose the Constable of Jerusalem unit or wish to recruit a new one, change any castle to a military-focused auto-build policy. It can be retrained at any castle but if you lose it completely, it is awkward to recruit again. You also get unique units like the very powerful Constable of Jerusalem, which is a “double strength” knightly unit. Templar Knights are also a small amount cheaper than Knights of Tripoli but slightly harder to retrain. Templar Confrere Knights are merely a cheaper but harder to retrain version of Knights of Jerusalem. A fortress will be required before Templar Knights or Knights of Tripoli can be recruited.
The Knights of Jerusalem are available early in the game and are relatively easy to retrain but the same cannot be said for the more powerful cavalry units. Mounted knights are the awe-inspiring anvil which the crusaders use to smash their enemies. Being a kingdom founded by Frankish crusaders, the Kingdom of Jerusalem shows many similarities with western European military norms.
In the harsh & unforgiving environment of Outremer, Christian Franks fight & die to preserve their “holy land” against the Muslim hordes who themselves considered Jerusalem to be a holy city.
