In 1847, a civil war broke out between the Catholic and the Protestant cantons (Sonderbundskrieg). Its immediate cause was a 'special treaty' (Sonderbund) of the Catholic cantons. It lasted for less than a month, causing fewer than 100 casualties. Apart from small riots, this was the latest armed conflict on Swiss territory.

As a consequence of the civil war, Switzerland adopted a federal constitution in 1848, amending it extensively in 1874 and establishing federal responsibility for defence, trade, and legal matters, leaving all other matters to the cantonal governments. From then, and over much of the 20th century, continuous political, economic, and social improvement has characterized Swiss history.