All Quiet on the Western Front is a novel by Erich Maria Remarque, a German author and World War I veteran. In this book, Remarque exposes what he believes is the true face of war.
In the book, Remarque highlights the damaging aspect of nationalism. He believes that this ideology pushed many soldiers to fight, and many leaders and commanders to engage in a war that brought very little benefit and advantages to most people, and instead, caused enormous pain and suffering.
It is likely that Remarque wanted to show such a harsh and cruel perspective on war in order to show that wars are rarely worth the destruction and suffering they bring. He most likely also wanted to show how war was like to people who were involved in it, and who were affected by it the most.