What is important about the line at the end of the section describing Kat's death-"Then I know nothing more"?All Quet on the Western Front by Erich Maria Remarque
Although the war is near its end, Germany continues to fight even though there is no hope of winning. The men feel as though they are prisoners sentenced to death; they fight at the front, then they wait to fight again. Paul has a sense of things falling apart as Detering finds a cherry tree and takes a branch with him as he heads home, going AWOL. Another soldier, Berger, jumps out of the foxhole to save a dog and is killed; Mueller is shot in the stomach and takes a half an hour to die. Everthing is "heroic and banal" Paul remarks.
Left with only Kat, who has been hit in the shin while bringing food, Paul must carry him to a dressing station because he bleeds too much. As he stops to rest, Paul talks to his dear friend, exchanging addresses.
Kat my friend, Kat with the drooping shoulders, and the poor, thin moustache. Kat with whom I know as no other man, Kat with whom I shared these years--it is impossible that perhaps I shall not see Kat again.
Sadly, on the last leg of the trek to the dressing station, Kat has caught a splinter in the back of his head and is dead when they arrive. Paul is incredulous; he feels hopelessly bereft without his friend. As he looks around "all is as usual," but all is really not. Without Kat to share with, to talk with, Paul has no one by whom to measure himself, to keep himself sane: "Then I know nothing more," he narrates. Nothing has meaning without his friend. At this point, Paul may also have fainted as the impact of losing his friend has put all into a state of senselessness and in his fatigue and grief he loses consciousness.