So what happened to the Whigs? The antebellum political party died a slow death from 1845 to 1854. First, President James K. Polk provoked a morally bankrupt war with Mexico in 1845, annexing Texas, and extending the nation’s borders to California’s Pacific coastline along the way. The addition of so much new territory so quickly drove questions about slavery that moderate Whigs and Democrats alike had dodged for thirty years from the abstract into the public square. On the one hand, many Americans (mostly northern and middle western, mostly Whiggish) argued that slavery should not spread to any new states formed from the territories stolen from Mexico. To the contrary, many other Americans (mostly southern, mostly Democratic) argued that slaves were a legitimate form of constitutionally protected property that could not legally be excluded from territory won using the common treasury and national armies. The discovery of gold in California in 1849 only added fuel to the partisan fire because it inspired so many people to head west in search of fortune, hastening that state’s ability to meet the demographic requirements for admission to the Union, and forcing the country at large to grapple with questions for which it was unprepared. Thus, the contest was joined over the central issue that was to dominate all American political life for the next dozen years, namely, the disposition of the territories. For the moment, moderates who desperately longed for a compromise that might stifle the underlying issue of slavery held the majority. However, it is a truism that happens to be true that, in crises of this sort, extremists grow in power, swallowing up all political space in the conciliatory center....