The player picks one of their units and announces which enemy unit it will charge. The enemy must make its charge reaction before another charge can be declared.

Charging is the only way for a unit to engage the enemy in close combat. It is up to the player if they wish to declare a charge or not, unless specified.

To declare a charge you must indicate which of your units is charging, and which enemy unit it is going to charge. You're always allowed to measure the distance between the charger and the potential target before declaring the charge, as this might well affect your decision whether or not to declare a charge.

When you declare a charge, one or more of the models in your unit must be able to trace a line of sight to the enemy unit, and the target must lie at least partially within the charging unit's front arc.