He is in the trench as he is thinking about all the memories he has had and he stands up to let the enemies shoot him and end his life. This was indirect suicide because he let the enemies get to him. This is when Paul loses all humanity because suicide shows Paul completely lost it. This event shows that Paul could control his anger with the war but after all these hardships, he could not handle the war and took his own life. If Paul kept his humanity, he would not end his life because he should know it will get better. Paul does not understand that which shows his humanity is completely