The Federal Constitution of the United Mexican States of 1824 (Spanish: "Constitución Federal de los Estados Unidos Mexicanos de 1824" ) was enacted on October 4 of 1824, after the overthrow of the Mexican Empire of Agustin de Iturbide.
 In the new constitution, the republic took the name of United Mexican States, and was defined as a representative federal republic, with Catholicism as the official and unique religion.
 It was replaced by the Federal Constitution of the United Mexican States of 1857.
Thirteen referendums were held in Switzerland during 1994.
 The first five were held on 20 February on federal resolutions on roadbuilding, continuing existing truck tolls and varying tolls based on engine power or mileage, as well as a popular initiative "for the protection of the alpine region from through traffic" and an amendment to the aeronautical law.
 All five were approved by voters.
 The second set of referendums was held on 12 June on federal resolutions on an article on the Swiss Federal Constitution on the promotion of culture and a review of the procedure for naturalising young immigrants, as well as a federal law on Swiss troops in peacekeeping operations.
 Whilst the resolutions were both approved by a majority of voters, they did not receive the approval from the majority of cantons, so were rejected, as was the law on troops.
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 in Switzerland, 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 constitution represents the first time that the Swiss were governed by a strong central government instead of being simply a collection of independent cantons bound by treaties.
Nine referendums were held in Switzerland in 1975.
 The first was held on 2 March on an amendment to the Swiss Federal Constitution on the article on the economic cycle.
 Although it was approved by a majority of voters, it did not receive the support of a majority of cantons (the result was an 11–11 tie), so was rejected.
 The next five were held on 8 June on protecting currency (approved), financing the national road network (approved), amending the general tariff (rejected), increasing taxes the following year (approved) and restricting federal expenditure (approved).
 The final three were held on 7 December on a constitutional amendment on the right to residence and welfare benefits (approved), a constitutional amendment on water management (approved) and a federal law on the import and export of agricultural goods (approved).
The Sonderbund War (German: "Sonderbundskrieg" ) of November 1847 was a civil war in Switzerland, then still a relatively loose confederacy of cantons (states).
 It ensued after seven Catholic cantons formed the "Sonderbund" ("separate alliance") in 1845 to protect their interests against a centralization of power.
 The war concluded with the defeat of the Sonderbund.
 It resulted in the emergence of Switzerland as a federal state, concluding the period of political "restoration and regeneration" in Switzerland.
Nine referendums were held in Switzerland during 1996.
 The first five were held on 10 March on revising article 116 of the Swiss Federal Constitution regarding language, abolishing the cantons' responsibilities for providing army equipment, abolishing the federal requirement to purchase distilling equipment, abolishing federal financing of parking areas at rail stations, and whether municipality of Vellerat (then part of the canton of Bern) should become part of the canton of Jura.
 All proposals except the one regarding army equipment were approved.
The Protestant Reformation in Switzerland was promoted initially by Huldrych Zwingli, who gained the support of the magistrate (Mark Reust) and population of Zürich in the 1520s.
 It led to significant changes in civil life and state matters in Zürich and spread to several other cantons of the Old Swiss Confederacy.
 Seven cantons remained Roman Catholic, though, which led to inter-cantonal wars known as the Wars of Kappel.
 After the victory of the Catholic cantons in 1531, they proceeded to institute counter-reformatory policies in some regions.
 The schism and distrust between Catholic and Protestant cantons would define their interior politics and paralyse any common foreign policy until well into the 18th century.
The legal basis of official statistics in Switzerland is the Swiss Federal Constitution.
 Article 65 of the Swiss Federal Constitution sets out the mandate and competencies of official statistics.
Fundamental Rights in the Federal Republic of Germany ("German: Grundrechte") are a set of rights guaranteed to everyone in Germany and partially to German people only through their Federal Constitution, the "Grundgesetz" and the constitutions of some of the States of Germany.
 In the Federal Constitution, the majority of the "Grundrechte" are contained in the first title, Articles 1 to 19 of the Grundgesetz (GG).
 These rights have constitutional status, binding each of the country's constitutional institutions.
 In the event that these rights are violated and a remedy is denied by other courts, the constitution provides for an appeal to the Federal Constitutional Court ("Bundesverfassungsgericht") (Art. 93 (1) (4a) GG).
The Federal Constitution of the Swiss Confederation (SR 10, German: "Bundesverfassung der Schweizerischen Eidgenossenschaft (BV)" , French: "Constitution fédérale de la Confédération suisse (Cst.)"
 , Italian: "Costituzione federale della Confederazione Svizzera (Cost.)"
 , Romansh: ' ) of 18 April 1999 (SR 101"') is the third and current federal constitution of Switzerland.
 It establishes the "Swiss Confederation" as a federal republic of 26 cantons (states).
 The document contains a catalogue of individual and popular rights (including the right to call for popular referenda on federal laws and constitutional amendments), delineates the responsibilities of the cantons and the Confederation and establishes the federal authorities of government.

Question: What event brought seven Catholic cantons of Switzerland together to create a federal constitution?
Answer: Sonderbund War