The protagonist never actually sets foot on a trench nor arrives at the front. It seems like the author died before he got to that

However, somebody did finish the novel; some dude made a second part after the author died, called Švejk in Russian Captivity and Revolution. I couldn't actually read it, because I only found the Czech version on the Internet, but I found a synopsis of sorts: the protagonist, Švejk, ends in Russian captivity, tries to escape, and ends up joining the Russian revolutionaries against the Tsar. Then he manages to return home. I think that's the best ending I can aspire to