The Sonderbund was a defensive alliance formed in 1845 by seven cantons in Switzerland. These cantons, primarily Catholic, aimed to protect their interests against the growing influence of the Protestant cantons and the centralizing policies of the federal government. The alliance was a response to political tensions and cultural differences within the country. The Sonderbund conflict escalated into a civil war in 1847, known as the Sonderbund War. The federal government, supported by the Protestant cantons, defeated the Sonderbund forces in a brief but decisive conflict. This victory led to the strengthening of the Swiss federal state and the eventual adoption of the Swiss Federal Constitution in 1848.