In the position in which the Tanks lay, the crews were able to train their 6-pounders against the enemy, who had been seen massing in the Wanbeke Valley. As the Lewis guns could not be brought to bear, they were dismounted, and the rest of the crews operated them from neighbouring shell-holes. [25]“Word was sent to the infantry to warn them of the coming attack, and to ask for co-operation. They replied that they had run short of ammunition for their Lewis gun, and some was supplied to them from the Tanks.” The attack did not develop as early as had been expected, but when it came it was in force. From about 6.30 onwards the enemy repeatedly attempted to advance, raking the Tanks with a hail of armour-piercing bullets, which, however, failed to penetrate. They were driven off every time with heavy loss, until at 11.30 a.m. our artillery opened and dispersed them with barrage fire. III The failure of their armour-piercing bullets against the Mark IV. must have proved something of a disappointment to the enemy. It is curious to trace the effort which the Germans made to keep up with our development of the Tank. For once, we had moved first, and the enemy was always to be a lap behind. No sooner had he discovered how effective was his “K” bullet against the Mark I. Tank, than we confronted him with the Mark IV., against which it was powerless. The Germans always had rather hazy ideas as to the capabilities and habits of our current Tank. They had had ample opportunity of examining two Tanks which lay derelict in their lines on the Somme, yet until the Battle of Arras they believed that Tanks were largely dependent on the use of roads, and that therefore pits and other obstacles in roads must form a useful anti-Tank defence. [26]“It was also not till the later stages of the Battle of Arras that the enemy realised from some captured Tanks near Bullecourt that the ‘K’ bullet was effective against the type of Tank that had been in use against them since September 1916. “By the time the enemy had fully realised this, however, the old Tanks were used up, and at Messines the Mark IV. had made its appearance and the chance of the armour-piercing bullet was over.... “After Messines the Germans began to realise the importance of artillery as a defence against Tanks, and ‘the chief rôle allotted to the infantry was to keep its head’ and leave the rest to the guns.... “Prominence was given to indirect fire[27] of guns of both heavy and light calibres on approaching Tanks. In spite of several dawn attacks the enemy laid great stress on what he called ‘Distant Defence,’ and a few special anti-Tank guns, about two per divisional front, were placed in specially covered positions.” It was not till the Battle of Cambrai in November 1917 that he was to discover by chance the one effective weapon against Tanks. That is to say, Direct Fire by field guns. THE “HUSH” OPERATION I