As the novel begins, it seems that Josef Švejk will not be required to do military service during World War I. Europe is reeling from the assassination in Sarajevo, but Švejk is not sure which “Ferdinand” everyone is talking about. Once his neighbor Mrs. Muller helps him get the story straight, he is not surprised. He credits a man he met in a bar with predictions about future political violence.

You mark my words, Mrs. Muller, they’ll get the Czar and Czarina yet, and maybe, though let’s hope not, the Emperor himself, now that they’ve started with his uncle. The old chap’s got a lot of enemies . . . A little while ago a gentleman in the saloon bar was saying that there’d come a time when all the emperors would get done in one after another, and that not all their bigwigs and such-like would save them.

This dialogue sets the stage for the way Jaroslav Hašek equivocates about Švejk's intellectual capabilities. He espouses no political views of his own, but reports hearsay and speculates about matters that he apparently does not understand. This kind of talk gets him in trouble, however, when he shares such opinions with a policeman, who arrest him for high treason. In court, the judge is not satisfied with his answers and cannot determine if he is faking having a low intellect in order to stay out of jail, so he is sent for a medical examination. In this scene, the absurdity of the novel is well established. A board of three experts ask him progressively more ludicrous questions, which Josef parries with his own type of logic.

“Is radium heavier than lead?”

“I’ve never weighed it, sir,” answered Schweik with his sweet smile.

“Do you believe in the end of the world?”

“I’d have to see the end of the world first,” replied Schweik in an offhand manner, “but I’m sure it won’t come my way to-morrow.”

After Švejk finally does end up in the army, he gets moved around quite a bit, creating a moderate stir as he manages to confuse even the simplest orders. As the good soldier interacts with various military personnel, Hašek’s indictment of the military is evident in his descriptions of officers such as Colonel Kraus.

The remarkable thing was that such an imbecile as this should have gained comparatively rapid promotion. During manoeuvres he performed regular miracles with his regiment. He never got anywhere in time, he led the regiment in column formation against machine-gun fire, and on one occasion several years previously, during the imperial manoeuvres in southern Bohemia, he and his regiment got completely lost. They turned up in Moravia, where they had wandered about for several days, after the manoeuvres were all over.

Throughout the novel, Švejk frequently serves as an orderly to Lieutenant Luká, who sometimes appreciates his dogged devotion but more often loses patience with his misunderstanding of instructions. On one occasion, however, Luká is absolutely smitten with a married woman he meets and, after having drunk too much, writers her an amorous letter, which he unwisely gives to Schweik to deliver. He swears the soldier to secrecy. Setting out on his errand, he immediately runs into an old friend, proudly announces he’s on a secret mission, and goes off to spend time wining and dining with him. When he finally settles down to delivering the letter, he reminds his friend how secretive he’s been.

“Didn’t I tell you when we was in that pub where that Czech barmaid is that I’m taking a letter to her from my lieutenant, and...