Ingersoll published the first novel, Travels and adventures of Little Baron Trump and his wonderful dog Bulger, in 1889, and its sequel, Baron Trump's Marvelous Underground Journey, in 1893. The novels recount the adventures of the German boy Wilhelm Heinrich Sebastian Von Troomp, who goes by "Baron Trump", as he discovers weird underground civilizations, offends the natives, flees from his entanglements with local women, and repeats this pattern until arriving back home at Castle Trump. The novels were part of a trend in American children's literature that responded to the demand for fantastic adventure stories triggered by Lewis Carroll's Alice in Wonderland (1865).
In July 2017, the books were rediscovered by Internet forum users, and then the media, who amused themselves by highlighting perceived similarities between the protagonist and U.S. President Donald Trump, whose son is named Barron Trump. Jaime Fuller wrote in Politico that Baron Trump is "precocious, restless, and prone to get in trouble", often mentions his massive brain, and has a personalized insult for most people he meets. Chris Riotta noted in Newsweek that Baron Trump's adventures begin in Russia, and also mentioned another book of Ingersoll's, The Last President, in which the president's home city of New York is riven by protests against a rigged presidential election.