The rise of Switzerland as a federal state began on 12 September 1848, with the creation of a federal constitution in response to a 27-day civil war, the Sonderbundskrieg. The constitution, which was heavily influenced by the United States Constitution and the ideas of the French Revolution, was modified several times during the following decades and wholly replaced in 1999. The 1848 constitution represented the first time, other than when the short-lived Helvetic Republic had been imposed, that the Swiss had a central government instead of being simply a collection of autonomous cantons bound by treaties.