The list of units
Leaders can arise when an elite unit wins a battle. The leader may be used either to create an Army or to hurry production in a city. When the leader does either of these things it disappears.
The Heroic Epic increases the chances of Leaders appearing.
Throughout history special individuals have come to prominence on the world stage. Each embodied in some way the ideals and dreams of their people, causing legions to follow their lead. These great leaders of mankind were capable of feats that created benefits well beyond what they could achieve by themselves. On the battlefield, they inspired their troops to conquer their fear and accomplish goals thought impossible. Within civilian society, these figures corralled diverse goals and opinions into a powerful, unified focus. Once organized, these social entities became capable of pushing their society steadily into the bright future they all hoped to visit.