 In a new manual of 1 December 1916, Grundsätze für die Führung in der Abwehrschlacht im Stellungskrieg (Principles of Command for Defensive Battle), the policy of unyielding defence of ground regardless of its tactical value, was replaced by the defence of positions suitable for artillery observation and communication with the rear, where an attacking force would "fight itself to a standstill and use up its resources while the defenders conserve [d] their strength". Defending infantry would fight in areas, with the front divisions in an outpost zone up to 3,000 yards (2,700 m) deep behind listening posts, with the main line of resistance placed on a reverse slope, in front of artillery observation posts, which were kept far enough back to retain observation over the outpost zone. Behind the main line of resistance was a Grosskampfzone (battle zone), a second defensive area 1,500 – 2,500 yards (1,400 – 2,300 m) deep, also sited as far as possible on ground hidden from enemy observation, while in view of German artillery observers. A rückwärtige Kampfzone (rear battle zone) further back was to be occupied by the reserve battalion of each regiment.
