S: (n) fire, firing (the act of firing weapons or artillery at an enemy) "hold your fire until you can see the whites of their eyes"; "they retreated in the face of withering enemy fire"
S: (n) operation, military operation (activity by a military or naval force (as a maneuver or campaign)) "it was a joint operation of the navy and air force"
S: (n) activity (any specific behavior) "they avoided all recreational activity"