From 6.30 a.m. onwards the enemy made repeated attempts to advance, shooting at the tanks with a large number of armour-piercing bullets which failed to penetrate. They were driven off in every case with heavy casualties, until at 11.30 a.m. our artillery barrage opened and dispersed them.
The battle of Messines, one of the shortest and best mounted limited operations of the war, was in no sense a tank battle. Tanks took but a small part in it, except in its final stages, nevertheless many useful lessons were learnt, the chief of which were: the necessity of some special form of unditching gear; the advisability of selecting starting-points well behind our front line (in this battle they were chosen too close behind it, with the result that as it was still dark at zero hour several tanks got ditched in “No Man’s Land”); the advisability of selecting rallying-points well behind objectives, so that when tanks have finished their work their crews may gain as much rest as possible.
The battle of Messines may be looked upon as the high-water mark of the artillery attack, which was first developed by the British Army during the battle of the Somme. The time, however, was approaching when a change of tactics became imperative on account of the enemy having learnt his lesson. To appreciate what this question involves is of some interest, especially so, as in the tank was eventually discovered a means of overcoming the counter-measures now adopted by the enemy.[24]
The main characteristic which differentiates the German defensive tactics of 1917 from those of 1916 would appear to lie in the grouping of their men rather than in the siting of their trenches.
In 1916 the major portion of the German Army was placed in the frontal defensive belt because security was sought for in the maintenance of an unbroken front. In 1917, however, this security was more economically guaranteed by holding behind this front, instead of in it, a large reserve which could strike at any opponent who broke through.
This reversion to the “big idea” and the abandonment of the smaller one, namely, that war is a “series of local emergency measures,” placed a further difficulty in the way of the attacker. In 1917 it was no longer a question of breaking through a defensive line as in 1914, or a zone of defences as in 1915 and 1916, but of exhausting the enemy’s reserves before undertaking either of these operations with decisive effect.