Control groups are a game mechanic that simplifies the process of organizing groups of units. Holding Ctrl and pressing any number key will assign the current selection to that number. The player can reselect this group at any time by pressing the associated number key. Pressing it again will center the camera on that group, and pressing it a third time will zoom in on that group.

The number a group is assigned to and the units that make up the group will determine the group's name. Groups consisting of mostly foot units will be classified as Infantry, groups that consist mostly of horses will be called Cavalry, groups of naval units will be called Fleets, and so on. The number they are assigned to will add the appropriate prefix (1st Infantry, 2nd Cavalry, 3rd Artillery, etc).

Creating groups is essential for leading multiple armies into battle, as it allows the player to quickly issue orders to multiple advancing formations. With enough skill, a good commander and quickly overwhelm an enemy by using this tactic.

Buildings can also be assigned control groups. Creating a control group with no units selected saves the camera position.

By default, F1 is assigned to your first city. You can continue this pattern by assigning F2 to your second city, etc.

Hint To add units to an existing group, hold Shift to add them to the current selection, then assign the group to the same number key it was on.