Pravane holds the claim to be the first published SteamPunk work. You can read a full review of the book here.
Comprising a cycle of linked stories set in Dorset, England, it depicts a 1968 in which the Roman Catholic Church still has supremacy; in its timeline, Protestantism was destroyed during wars that resulted from the aftermath of the assassination of Queen Elizabeth in 1588.
Without Protestant England, Spain prevented the Protestant Netherlands from attaining independence, while the German mercantile city states that financed the Reformation were also suppressed. As a consequence, while Spanish power eventually wanes, the Roman Catholic Church has no rivals and the Pope becomes the effective secular, as well as spiritual, ruler over Europe (a development with no parallel in the actual history of Catholic countries). The Church thus also controls the restive “New World” (which approximates the United States in our timeline), as well as “Australasia”, where James Cook planted the cobalt flag of the Vatican, instead of the Union Flag in the eighteenth century.