But nightfall did not bring a cessation of the bombardment. Every few minutes throughout the night the shells cut new gaps. Work was impossible. Tom guessed that the enemy’s object was not merely to prevent repairs, but to wear the defenders out by breaking their rest and keeping them constantly on the watch. In one way, however, the persistent bombardment was a source of satisfaction to him. While the shells continued to fall, there was no likelihood that the enemy would again assault. The prospect of a night attack had caused him much anxiety, for the negro’s morale is never at its best in the dark; further, in darkness and confusion the weight of numbers would tell heavily against him. Tom knew nothing about artillery, and began to feel a certain contempt for the gun, so slight was the material damage done by its shells. It was not, however, a field gun, but a small mountain gun, more easily transportable than a larger weapon. After the bombardment had continued for some hours neither he nor the men were much disturbed by the shell bursts, and he felt more and more confident of his ability to hold his own. But when daylight came again he discovered that the enemy had had another purpose in their shelling. The bombardment continued. The scouts from their high posts above reported that they saw men’s heads in the ground on the further side of the clearing. Unable to make out what they meant, Tom climbed the side of the nullah under cover of the bushes until he reached the trench, and cautiously looked out across the open space beyond the barricade. Some thirty yards in advance of the edge of the forest, on the level of the ground, he saw the heads of several askaris moving up and down. At one moment a dozen heads were in sight, the next some of them disappeared, only to bob up again a few seconds later. "By George, they’re digging," he said to himself. Quite ignorant of all military operations except those simple manoeuvres learnt in the course of field days with his school cadet corps, he was at first at a loss to understand why the enemy were digging a trench which was apparently to extend from the forest to the nullah. He had perhaps heard the word sap, but it conveyed nothing to his mind. It was not long, however, before he guessed the meaning of this unlooked-for movement. The enemy were digging a means of approach by which they would avoid the inevitable losses of a rush across the open, and the bombardment during the night had been designed partly to cover the sounds of their tools. Watching intently, he noticed that the direction of the enemy’s trench was not a straight line towards the barricade, but a series of short zigzags, obviously to minimise the risk of interference by enfilading fire. "I ought to try to stop that little game," he thought.