Surviving the war

As time goes on in Three Day Road Xavier learns to accept the fact that he is at war with the Germans and as time goes on he sees his friends and fellow soldiers fall everyday until the day comes when he fires back, he does not miss. Xavier's first kill is a German sniper who has been evading everyone and getting many Canadian kills up and down the lines. After this Xavier understands that they are the enemy and they are always there waiting for a chance to kill him. Further into the war Xavier starts causing more damage to the german machine gun nests and the german front line hitting everything he sets his sight on. Even though Xavier does the hardest shooting Elijah takes the credit making Xavier mad.
I wonder why Xavier himself does not tell Breech and Mccaan of the soldier he has shot and of the machine guns nests he has destroyed. Part of the reason I think is because he doesn't want to be known as a killer even though it would gain him more respect from Breech and Mccann. Elijah even though he tries to show of and brag about what he has done he knows Xavier has always been a better shot and sniper than Elijah.
I now know why and how Xavier loses his leg it is unexpected. I also know what happens to Elijah it is very unexpected. The question i have is what made Xavier lose his mind and do what he did. I would explain but i do not want to spoil the ending.All I have to say to wrap up is that the war took a huge toll on everybody some let it show and some kept it hid until they exploded in the end.