After the upheavals of the early 1830s, conflict between radical liberals and conservative – generally Catholic – activists led to increasingly bitter squabbles. After Aargau overturned the constitutional equality of Protestantism and Catholicism in 1841 and ordered all religious buildings in the canton to be shut down, outraged Catholics in neighbouring Luzern nullified that canton’s newly drafted liberal constitution and – in a move intended to provoke – invited the Jesuit order to run the canton’s schools. This, in turn, outraged radical opinion, which valued liberal education highly and viewed Jesuit control of the schools as nothing less than a backward step into superstition.

Violent, radical-led scuffles soon broke out, aimed at Luzern’s Catholics. In response, the Catholic cantons – Luzern, Zug, Schwyz, Uri, Obwalden, Nidwalden, Fribourg and Valais – formed an illegal resistance force, dubbed the Sonderbund (Separatist League), which threatened to destabilize the country. During 1846, a series of localized revolutions put radicals in control of more and more cantons nationwide until, by 1847, with a majority in the Diet, they demanded the expulsion of the Jesuits from the country, the drafting of a new democratic constitution, and the forced dissolution of the Sonderbund. Civil war was inevitable, and – as much to head off potentially disastrous intervention by the great European powers as anything else – the federal commander in chief General Henri Dufour took the opportunity to strike rapidly and effectively. In a month-long campaign during November 1847 he easily took Fribourg and Zug, and then Luzern, crushing the heartland of the Sonderbund with casualties barely in three figures. The remaining Catholic cantons capitulated following the decisive Battle of Gislikon at the end of November.