A charge is an action in battle in which soldiers advance towards their enemy at their best speed to engage in close combat. The charge has been the key tactic and decisive moment of most battles in history.
The basic process operating in a charge is speed of advance against rate (or effectiveness) of fire. If the attackers advance at a more rapid rate than the defenders can kill or disable them then the attackers will reach the defenders. When a charge was not successful that will often leave the would-be attackers extremely vulnerable to a counter-charge.