Many great authors have depicted the glory, chivalry, horror, and morbidity of warfare. The novels Slaughterhouse Five and Beau Geste depict very different ideals of war and the undeniable consequences of military service.
The foremost and most obvious difference is the way in which the two authors portray their main characters. Vonnegut's Billy Pilgrim defies any conventional mold of a wartime hero. Originally enrolled as chaplain, Pilgrim's intentions weren't to fight, but to serve the moral and spiritual needs of the soldiers. As he finds himself far away from his squadron, wondering aimlessly in the German woods with other American soldiers, he's forced to endure hardships unbeknown to his character. One of the soldiers, Roland Weary, slightly gun happy and quixotic in his visions of war heroes, often castigated Pilgrim for his lack of zeal in the survival effort. After reading the novel, one is more inclined to sympathize toward Pilgrim than consider him a noble soldier.
Wren's main character, John Geste, on the other hand is a dashing young English gentleman of nobility with many laudable traits. Geste is intelligent, well-breed, handsome, and virile. Often times throughout the novel, John is faced with unrealistic goals, such as fighting off bands of Arabs single-handedly and holding down the fort solo. It is obvious that Wren's ideal of the war hero is always victorious in the face of peril.
Furthermore, the motives behind the two battles/wars being fought in the respective books are of a different nature. Vonnegut's disdain for World War II is fairly blatant. Often throughout the novel, Vonnegut makes mention of the American bombing of Dresden, Germany, in which over one hundred thousand innocent Germans were slain. Also, the psychological and physical damage that.
Billy Pilgrim suffers illustrates the authors viewpoint that war is nothing short of bloody, physically exhausting, and in general useless.