It must have been clear to General Gough and to his corps commanders that a second day of battle, with the German reserves pouring up, would certainly mean a penetration of the line at these various weak points, and that the enemy would then be in a position to cut off large portions of the force. These units, be they divisions or corps, would no doubt fight to the last, but the end must surely be annihilation. In that case the general situation would have been an appalling one. It might indeed have been decisive for the whole war. There was nothing between the Germans and Amiens. Pouring westwards they would have destroyed all reserves almost before they could have alighted from their trains or their motors, and within a few days would have entirely cut off the British from the French, with the estuary of the Somme between the two armies. Any hesitation would have been fatal. An immediate decision was imperative. That decision could only be that the British Army should retard the German advance by an obstinate rearguard action, that it should endeavour to preserve its line, and allow no unit to be cut off, {115} that it should fall back in an orderly fashion upon its reserves, and that when it met them it should turn at bay and prevent the enemy from reaching his objective. This was the plan which General Gough instantly formed, and which he proceeded with firmness and moral courage to carry out. Orders were at once given that the weaker portions of the line should drop back behind the obstacles which had already been marked out as the best defensive lines. At the same time with great foresight he gave orders that the old French Somme trenches, from the river southwards, should be set in order as a last line of defence. He despatched his chief army engineer, General Grant, to carry out this order, and it was eventually a very vital one in ensuring the safety of the army in the last stages of its retreat.