Susan Jacoby wonders why the 19th century's "Great Agnostic" Robert G. Ingersoll was more or less forgotten to history. One theory she suggests: it was liberals' smug confidence in their victory over fundamentalism after the Scopes trial.
Ingersoll's collected works were published within a few years of his death [in 1899] by his brother-in-law C. P. Farrell, who owned the Dresden Publishing Company (named for Ingersoll’s birthplace in upstate New York). The Great Agnostic remained a well-known, frequently cited figure into the 1920s, not only because many of his friends and enemies remained alive but also because his writings were still thought to be capable of corrupting American youth.
The memory of Ingersoll faded swiftly, however, after the famous 1925 Scopes Monkey Trial, which pitted the leading spokesman for religious fundamentalism, William Jennings Bryan, against Clarence Darrow, the nation’s most famous criminal lawyer and an equally famous agnostic, who had been strongly influenced by hearing Ingersoll’s speeches in the 1870s and 1880s.Jacoby has a biography of Ingersoll coming out in 2013.
I'm slightly suspicious of the question, here. There's an assumption that it's odd or abnormal for Ingersoll's presence to have faded or have been forgotten, an assumption that goes to support Jacoby's thesis about Ingersoll's significance without making an argument for his importance.
There is an interesting question here, though. To what extent did the "victory" in the Tennessee court house, as understood by those who were critical of religion, as represented by them to themselves, change the shape of skeptical arguments and the development of the atheistic cause?