Age of Chivalry: Hegemony can be found at http://aok.heavengames.com/blacksmith/showfile.php?fileid=9053. To download, you need Age of Empires II: The Conquerors Expansion, version 1.0c. The wiki for the Age of Empires Series on Wikia can be found here.
Age of Chivalry is hosted on both AoKHeaven and moddb. You can always find the latest version on those two sites. You can download it, and the language packs that have been released for it thus far, here: