Each body of the advancing enemy was under the command of a specially trained officer, whose leadership generally proved a model of skill and initiative; each detachment was instructed to push on as far as its strength allowed, and every man carried iron rations for several days. When a regiment had advanced as far as it was able, another took its place, the waves of the advance thus leapfrogging over each other in an endless chain. The dangers of such tactics are obvious, but on March 21 the system was portentously successful. II As in all disasters, events seemed to move with a terrible rapidity. A moment before the motor accident you are a free man; a moment after and you are involved in an endless line of consequences which have sprung up while you could hold your breath, and amid whose mushroom growth you may wander for the rest of your life. Five hours after the opening of the German cannonade the world seemed to have changed for the two armies which had stood in the path of the hurricane. In the course of the next fourteen days the Germans were to sweep forward for forty miles, and their advance was even then to be checked, not by the British Army, but by the gradual attenuation of their supply system. The whole fourteen days of the retreat were completely confused. Units were inextricably mixed, and communications were impossible. Some sort of immediate action was always having to be taken by junior Commanders on information which they justly believed to be untrustworthy. There were often more Germans to the flank of any given body than to its front. When we try to form any general conception of the events of this period, we seem to see the actors moving in a kind of mist from which they emerge for a moment, perform some action which may or may not appear relevant, and then disappear again into the confusion, leaving us to guess at the meaning of the play. As far as the events of such a time can be chronicled, we propose for this fortnight to follow separately the doings of the three Tank Battalions chiefly involved, and to make no effort to present a coherent picture of this return to the reign “of Chaos and old Night.” The 4th and 5th Battalions (4th Brigade) lay near Cartigny (south of Péronne). On the morning of the 21st the two Battalions of Tanks were moved up into the line, two Tanks of the 4th Battalion counter-attacking at Peizière and clearing a railway cutting of the enemy. On the 22nd all the Tanks were ordered into action. The infantry were retreating, and their chief duty was to gain time and to cover that retreat. Twelve Tanks of the 5th Battalion attacked the enemy at Hervilly Wood, and several from the 4th Battalion near Epehy. Both detachments suffered rather severely. At this point the two Battalions seem to have more or less parted company. Seventeen Tanks belonging to the 5th Battalion rallied at Cartigny that night, and next day (the 23rd) were ordered to retire over the Somme.