This document provided general guidance for the conduct of the defense and, with subsequent editions, became the German doctrine of defense for the rest of the war. OHL officially rejected the principle of holding the forward line at all cost. The regulations now stated that the objective of defense was to force the attacker to frustrate and expend himself, while the defender pre- served his strength. The Principles related the purpose of the defense entirely to the enemy and did not mention retention of terrain as the basic objective. The principles for achieving the objective were:
o The defender must not surrender the initiative to the attacker. e
The defense must rely on firepower, not large numbers of troops. l
The defender must not hold ground at all costs (a controversial principle). 0
The defender must consider depth for all construction and positions.50
Previous concern with the inviolability of the front line had caused the Germans to strengthen that part of the battlefield within range of Allied artillery and where the Allies applied their maximum power to achieve a pene- tration, that is, on the forward edge. The range of artillery and the fieIds of artillery observation favored the Allied concentration of artillery on the Ger- man forward edge. With the new German doctrine, the Allied concentration of firepower was on a forward edge held by relatively few German troops. Ger- man strength no longer directly confronted Allied strength. As the Allied attack advanced, its relative power would deteriorate as the distance from its artillery support increased because the attack outran its inflexible communiea- tions system and eventually exceeded the range of its supporting artillery. As the Allied advance became more confused and weak as it progressed, German power increased, for the Germans positioned their forces in tiers or echelons which became stronger as the distance from the front line increased.
The outpost zone served a purpose similar to outposts in open warfare: to contain enemy raids and patrols, to provide warning of major attacks, and to disrupt those attacks. Behind the outpost zone was the front trench system, usually three successive trench lines, called the main line of resistance (MLR). This main line of resistance was the forward edge of the battle zone. The battle zone extended back, depending on terrain, fifteen hundred to three thousand meters, with a second trench line, the artillery protective line, as its rear boun- dary. Behind this trench system was the rearward zone, although the Germans later extended the battle zone to create even more depth. The artillery was organized in great depth behind its protective line.51
The major defensive battle would occur in the battle zone. The new regula- tions recognized that a massive enemy attack could overrun the MLR, but the regulations also stated that a counterattack in the battle zone would recover the MLR. Several factors favored the defender in this critical struggle. In keep- ing with the philosophy of using firepower to inflict maximum enemy casual- ties, the Germans fully integrated artillery into the defense. The PrincipZes (1 March 1917 edition) devoted more pages to artillery than to any other combat arm. The tactical considerations for selecting defensive positions were not placement of infantry units, but “observation and positions for artillery, andcommunications with the rear,“s2 which clearly established the role of artillery as crucial in the defense. German artillery observers would have the battle zone under observation, but Allied artillery observers would be unable to direct their own artillery fire because of the masking terrain concealing the German MLR. As the Allies advanced beyond the range of their own artillery support, the Germans responded with carefully planned, timely artillery fire.
The German soldiers in the outposts and the main line of resistance, how- ever, were not simply given carte blanche to evacuate their positions and head for the rear at the first opportunity. The defense was aptly called elastic, for it was to resist, bend, and snap back. The Principles stressed tenacity of defense, for ““stout hearted men with iron nerves form the real backbone of defense.“53 The flexibility given to soldiers in the forward areas was practical: they were to shift to escape the artillery fire, and survive in order to inflict casualties on the subsequent enemy infa’ntry assault. This shifting to escape Allied artillery could be to the flanks, to the rear, or to the front,54 and it usually occurred in the numerous shell holes. The Somme experience had shown that large elabo- rate positions had disadvantages under heavy artillery fire. The trenches were necessary for daily living, but once detected they were lathered with prepara- tory fire and barrages. Deep dugouts in forward areas were also impractical, for soldiers remained in them too long after the enemy barrage lifted and were often captured. Therefore, under heavy fire, the forward German soldiers evac- uated their trenches and shifted from shell hole to shell hole, avoiding concen- trations of fire and escaping the detection of aerial artillery spotters.
The Allied advance would first encounter resistance from pockets of Ger- man survivors in shell holes. Having been concealed from aerial observation, units positioned on the reverse slope would then open fire unexpectedly.55 The Allies would also encounter fortified strongpoints (Widerstandsnester). These strongpoints were not deep dugouts as before, but less elaborate fortified posi- tions (of earth, wood, old buildings, or anything else available) for squads or machine gun sections, carefully sited to avoid Allied observation. Placed mostly in the battle zone, they were built to provide for all-around defense and they engaged the attackers, whenever possible, with devastating enfilade fire.s6 The strongpoints would remain fighting even if cut off by the enemy advance.
The ideal scenario was:
A fragmented, exhausted Allied attack force reaches the battle zone. They hope that their thorough artillery preparation has killed all the Germans, but they encounter several Germans firing at them from shell holes in the torn ground. Sudden fire from the German main line of resistance has slowed the Allies and their sheduled artillery barrage has crept forward without them, according to a timed sequence of fire they cannot modify. They feel helpless without artillery support. The Allies finally have taken the main line of resis- tance at great cost, but now they are in unfamiliar ground, under fire from concealed enemy machine gunners and riflemen. German artillery, which the Allies expected to destroy in the preparatory fires, now appears uery active.
The Germans concentrate their artillery fire behind the Allied advanced units, cutting them off from reinforcements and supplies. For the next feu! minutes, the Allies have a tenuous hold on a few acres of ground, but by advancing into the battle zone, the Allies are most uulnerable, and have exposed themselves to the counterattack, the soul of the German defense. The immediate counterat- tack, well coordinated with accurate artillery fire, destroys, captures, or ejects the Allied unit before it can consoh‘date its gain,s. The coherence of the German defense is restored.