It will be seen that by this date the Tank Corps had grown from three to five brigades, in all thirteen battalions; machines, however, were short, and the total fighting strength in tanks at this time was only 320 Mark IV and 50 Medium A Tanks (Whippets) fit for action.
The general plan was that tank units should co-operate with Army and Corps reserves in the deliberate counter-attack against tactical points in what was known as the battle zone, a belt of ground running several miles in rear of and parallel to the forward or outpost zone; no retirement from this zone was to be contemplated. Prior to March 20 the weather had been fine, the ground was good and a thorough reconnaissance had been made of some 1,500 square miles of country; supply dumps had been formed and communication by wireless, cable, dispatch rider and runner established throughout the units of the Tank Corps.
On March 21 at 5 a.m. the German bombardment opened on a front roughly running from La Fère to the river Scarpe, with a break round the old Cambrai battlefield. The first tanks to be engaged were three forward sections of the 4th Battalion north-west of St. Emilie, north-west of Peizière, and at Geninwell copse. These came into action about noon and fought most gallantly against heavy odds. The first section, supported by two companies of the 2nd Royal Munster Fusiliers, recaptured a battery of guns near Esclairvillers wood; later on in the day this section assisted in the counter-attack of the Connaught Rangers on Ronssoy wood; meanwhile the second section cleared the bridge and cutting north-east of Peizière. Whilst these actions were being fought in the Fifth Army area, on the Third Army front one company of the 8th Tank Battalion co-operated with the 57th Infantry Brigade in a counter-attack on the village of Doignies. Zero hour was fixed at 6.40 p.m., but the attack was delayed and it was almost dark before the objective was reached. The village was cleared of the enemy, but on account of the darkness it was never completely occupied by our own men and eventually passed back into German hands.
On the following day, March 22, an Advanced Tank Corps Headquarters was opened at Hamencourt, a mile east of Doullens, in order to facilitate the battle liaison duties of the staff. On this day a most successful and gallant action was fought by the 2nd Tank Battalion in the neighbourhood of Vaux Vraucourt and Morchies. At 2.45 p.m. orders were issued for the 2nd Tank Battalion to advance and counter-attack the enemy, who had broken through the line Vaux Vraucourt-Morchies and was pushing forward towards Beugny. Two companies of infantry were detailed to support the tanks, but as eventually these could not be spared the tanks went into action alone. The counter-attack began to develop around Beugny at about 4.30 p.m. Concentrated artillery fire was brought to bear on the tanks, but in spite of this they advanced amongst the enemy, put a field battery out of action, and by enfilading several trenches full of Germans inflicted heavy casualties on them. The enemy was eventually driven back behind the Vaux Vraucourt-Morchies position, which was then reoccupied by our infantry. Thirty tanks took part in this action; seventeen of these were hit and 70 per cent. of casualties suffered by their crews. Heavy though these losses were the enemy had suffered severely, and more important still his plan of action was upset.