Chapter 13 of A Long Way Gone deals with the boys' introduction to actual combat. We see here just how they are turned from boys into mindless killers.
Ishmael and the others have just finished up their training and are given some time to behave like children once again. They play soccer and splash around in the river. Ishmael has a strange feeling that they will soon be made to fight, although it seems that the other boys are mostly unaware of this. It seems ridiculous to him that some of them can be asked to be soldiers. Sheku cannot even stand up under the weight of the ammunition he is carrying. Before heading out into the woods, they are given a pill to swallow, which they are told will energize them for combat.
Once Ishmael and the others head into the woods, it does not take them long before they engage the enemy. It is total chaos: Musa and Josiah are quickly killed. Ishmael starts firing his rifle and makes his first kill. He enters a rage and furiously kills a number of enemies.
When the shooting stops, Ishmael finds that he is no longer afraid of fighting and of the dead. He finds that he has no strong feelings at all anymore. He inspects the bodies of the dead enemies and casually rolls some of them over with his foot as if they were nothing different than any inanimate object.
At night, the drugs that he had taken before the battle wear off. Ishmael awakes from a nightmare and finds that he is firing his rifle inside of the tent. His lieutenant rushes over and gives him another pill to take, but he still cannot get back to sleep. There are two more battles that week, and Ishmael no longer has any trouble killing.