"Surprise is at all times the assailant's strongest weapon."--"Field Service Regulations," vol. ii. (1920).
The aim of every commander who possesses the power of manoeuvre is to seek out the enemy and destroy his organised forces. The Attack is the culminating point of all manoeuvres to this end, and every commander will endeavour to achieve his aim by a sudden and unexpected assault on a part of the enemy's defences.
The achievement of this aim is only possible when a commander has assembled a sufficient force for his purpose, and has obtained, by reconnaissance and by fighting, information as to the vulnerability of the hostile position. The commander will then endeavour to break the enemy's formation so suddenly as to disconcert all his plans; to retain a compact force with which to follow up the blow without giving the enemy a moment's breathing space; to drive a wedge into the heart of his disordered masses, forcing his wings asunder; and to pursue and annihilate the scattered forces of the enemy.
"Unless a decision is quickly obtained in the opening weeks of a modern campaign the opposing armies tend to become immobile, chiefly owing to the great power conferred on the defence by modern armaments. The armies will then be distributed in great depth, and the attackers are faced with the necessity of breaking through not one position only, but a series of positions, extending back to a depth of several miles" ("Infantry Training, 1921").
Penetration, followed by the sundering of the Franco-British Armies, was clearly the intention of the German { 52} High Command in the _Second Battle of the Somme_, which opened on March 21, 1918. The German Armies had entrenched themselves after the First Battle of the Marne (September, 1914), and for 43 months had been confronted by the Allied Nations of Britain, France, and Belgium, reinforced at the close by Portuguese troops and by the National Army of the United States.