Kat is the leader of the pack in almost every way. He's forty, mature, strong, and handsome and has a distinctive sixth sense in identifying trouble, which the other men admire greatly. In brief, he is that kind of man you want to be sent to war with and Paul knows how lucky he is that Kat has his back. Kat becomes Paul's closest friend and team-mate in the story. He believes in duty, despite not personally embracing the ideals of war. In fact, although he fights with as much heart as any of them, he has more than a little bit of contempt for the higher-ups who drive the war forward.
Stanislaus Katczinsky in the Essays