By 1908, when Jack London's The Iron Heel was published, many of the antecedents of Steampunk had already come into their own. H.G. Wells worked his magic in Britain, American science fiction started to come into its own, and Jules Verne was still popular even after his death three years prior.
The Iron Heel earns a special place in the canon of Science Fiction literature as possibly the earliest of the modern Dystopias. The tale follows one Avis Everhard from the year 1912 to 1932, during the initial rise and dominance of the socialist Oligarchy that would eventually control all of North America. The novel itself is based on the fictional "Everhard Manuscript," discovered some 700 years in the future. London makes use of a framing story based around the scholar Anthony Meredith, who writes from the year 2600 or (419 Brotherhood of Man by the story's reckoning). London thus writes two stories, one around Everhard and one around Meredith.
The introduction to the novel is "written" by Meredith, and consists of a huge spoilier in that he tells the reader how Avis Everhard and her husband Ernest were summarily executed for rebelling against the Oligarchs. The "Iron Heel" of the title refers to the Oligarchy that arose in the United States during the 1912 to 1932 time frame of the novel. The Oligarchs are the robber barons of the major business monopolies, who take over by bankrupting most small to midsize business and turning all the farmers into serfs. They control the country via a sort of labor caste and their mercenary army.
It's only in the railroad, steel, and other essential industries where workers receive decent wages, housing, and education. London proposes that it's because these industries broke solidarity with other labor unions that the Oligarchy was able to arise. The Oligarchy eventually comes to dominate North America for three centuries, until the revolution first started by the Everhards comes to fruition and the Oligarchy is overthrown.
The main story of The Iron Heel is that of Avis Everhard's autobiography. We follow her through her privileged childhood, the fall of the U.S. republic, her marriage to the socialist revolutionary Ernest Everhard, and their eventual failure to overthrow the Oligarchy. The future perspective of the historian, Meredith, only serves to deepen the tragic plight of the Everhards and their revolutionary comrades.
To Steampunk, stories like The Iron Heel give us the dark and dreary sense of a potential future where humanity is oppressed by some tyrannical force. Whether that's businessmen, governments, or something else is entirely up to the author. Either way, the bleakness of the human experience is what's important in a dystopia, and The Iron Heel has that in spades.
Tomorrow: The Roots of Steampunk Wrap Up