Following the Congress of Vienna (1814–1815), Switzerland's independence and permanent neutrality were formally recognized by the European powers. Three new cantons—Valais, Neuchâtel, and Geneva—joined the Confederation, expanding Swiss territory to its modern boundaries. The Federal Treaty (Bundesvertrag) of 1815 restored Swiss governance as a loose confederation of 22 cantons, each retaining significant autonomy.
Social and Political Challenges (1815–1840s)
Despite nominal peace, tensions between liberal Protestant and conservative Catholic factions intensified. The Restoration period saw many cantons revert to feudal privileges and conservative rule, reversing reforms introduced during the French occupation. However, liberal movements advocating for economic modernization and political reforms gained momentum, especially in the urban, Protestant regions.
The Free Democratic Party (Freisinn) became a powerful political force, pushing for centralization and progressive reforms. By the 1840s, the liberals gained control of the Federal Diet (Tagsatzung), proposing a new Swiss constitution to unify the cantons more closely and introduce protections for trade, education, and religious freedoms. This triggered fierce opposition from conservative, Catholic cantons that sought to preserve their autonomy and traditional religious structures.
Escalating Tensions: Formation of the Sonderbund (1845)
In response to liberal measures—such as the closure of monasteries in Aargau in 1841—seven Catholic cantons (Lucerne, Uri, Schwyz, Unterwalden, Zug, Fribourg, and Valais) formed the Sonderbund ("Separate Alliance") in 1845. Their goal was to resist further centralization and defend Catholic education, especially after Lucerne invited Jesuits to lead its schools.
The Sonderbund violated the Federal Treaty of 1815, which prohibited separate alliances among cantons. The Diet ordered its dissolution in October 1847, but the Catholic cantons refused to comply, setting the stage for a civil war.
The Sonderbund War (November 1847)
On November 3, 1847, the Swiss federal army—led by General Guillaume Henri Dufour—mobilized to dismantle the Sonderbund. The national army consisted of 100,000 troops from the Protestant and neutral cantons, while the Sonderbund mustered 79,000 soldiers. The conflict lasted less than a month, with major battles fought at Fribourg, Gisikon, and Lucerne. Despite early resistance, the Sonderbund forces were decisively defeated by November 29. The victors treated the defeated cantons with unexpected generosity, encouraging them to rejoin efforts toward national unification. The Sonderbund War resulted in only about 130 casualties and marked the last armed conflict on Swiss soil.
Aftermath and the Federal Constitution of 1848
Following the war, the liberal majority introduced the Swiss Federal Constitution of 1848, transforming Switzerland into a federal state with a centralized government. The new constitution ended the near-total independence of cantons and gave the national parliament control over trade, foreign policy, and defense. Jesuits were banned, and religious freedoms were strengthened to prevent future conflicts between Catholics and Protestants.
The victory of liberal forces in Switzerland inspired fear among conservative governments across Europe, contributing to the wave of revolutions in 1848. However, the Swiss model of peaceful resolution and cooperation became a foundation for the modern Swiss federal state, which has remained stable and neutral ever since.