Detachments must be deployed at the same time as their Regimental Unit, with at least one model from the Detachment within 3" of their Regimental Unit. If arriving as reinforcements, a Detachment always arrives with its Regimental Unit; the Detachment is deployed so that at least one model in the unit is within 3" of its Regimental Unit and their back touches the board edge.

If an enemy unit declares a charge against a Regimental Unit, and the Regimental Unit does not flee as a charge reaction, then each of its unengaged Detachments within 3" can make either a Support Fire or Counter Charge action. These actions are declared immediately after their Regimental Unit’s charge reaction. If the Regimental Unit does not get a charge reaction for any reason, then the Detachment cannot make a Support Fire or Counter Charge action. Additionally, a Detachment can only declare one Support Fire action, one Stand and Shoot reaction or one Counter Charge Action per turn.