Complex sentence: The basic idea of all tactics (land, sea and air) is "fire and movement": the fulfillment of a mission by the effective delivery of firepower resulting from scouting and the creation of good firing positions.
Split into simpler sentences: The basic idea of all tactics (land, sea and air) is "fire and movement". The fulfillment of a mission by the effective delivery of firepower resulting from scouting and the creation of good firing positions.