The Sonderbund War (German: Sonderbundskrieg) of November 1847 is a civil war in Switzerland, then still a relatively loose confederacy of cantons (states).

It ensues after seven Catholic cantons form  the Sonderbund ("separate alliance") in 1845 to protect their interests against a centralization of power.

The war concludes with the defeat of the Sonderbund.

It results in the emergence of Switzerland as a federal state, concluding the period of political "restoration and regeneration" in Switzerland.

The Sonderbund consists of the cantons of Lucerne, Fribourg, Valais, Uri, Schwyz, Unterwalden and Zug, all predominantly Catholic and governed by Conservative administrations.

The cantons of Ticino and Solothurn, also predominantly Catholic but governed by liberal administrations, o not join the alliance.

After the Tagsatzung (Federal Diet) declares the Sonderbund unconstitutional and orders it dissolved by force, General Guillaume Henri Dufour leads the federal army of one hundred thousan and defeats the Sonderbund under Johann-Ulrich von Salis-Soglio in a campaign that lasts only a few weeks, from November 3 to November 29, and claims fewer than a hundred lives.

He orders his troops to care for the injured, anticipating the formation of the Red Cross in which he will participate a few years later.

Major actions are fought at Fribourg, Geltwil, Lunnern, Lucerne, and finally at Gisikon,

Meierskappel, and Schüpfheim, after which Lucerne capitulates on November 24.

The rest of the Sonderbund surrenders without armed resistance in the subsequent weeks.