Currently, it is illegal for Swiss citizens to join another country's armed forces except as members of the Swiss Guard protecting the Vatican. Military service abroad of dual nationals is permitted under certain circumstances. Internal conflicts after the Reformation The Swiss peasant war of 1653 was a popular revolt by the rural populations of several cantons. The rebellion was suppressed, but it led to a series of reforms. In 1656, tensions between Protestants and Catholics re-emerged and led to the outbreak of the First War of Villmergen. A new conflict in 1712 caused the Second War of Villmergen, which overturned the balance of power to the Protestant cantons. The religious conflicts were renewed in 1847, resulting in the Sonderbund War and leading to the formation of Switzerland as a federal state. Helvetic Republic In 1798 the French army overran Switzerland and proclaimed the Helvetic Republic. Internal resistance and economic problems destabilized the state and additional French troops were deployed to restore order. Parts of Switzerland also became a battleground during the Italian and Swiss expedition. During the 1814-15 Congress of Vienna the neutrality of Switzerland was guaranteed by the signatories. Birth of the federal state In the federal treaty of 1815, the Tagsatzung prescribed cantonal troops to put a contingent of 2% of the population of each canton at the federation's disposition, amounting to a force of some 33,000 men. The cantonal armies were converted into the federal army (Bundesheer) with the constitution of 1848. From this time, it was illegal for the individual cantons to declare war or to sign capitulations or peace agreements. Paragraph 13 explicitly prohibited the federation from sustaining a standing army, and the cantons were allowed a maximum standing force of 300 each (not including the Landjäger corps, a kind of police force). Paragraph 18 declared the obligation of every Swiss citizen to serve in the federal army if conscripted (Wehrpflicht), setting its size at 3% of the population plus a reserve of one and one half that number, amounting to a total force of some 80,000. The first complete mobilization, under the command of Hans Herzog, was triggered by the Franco-Prussian War in 1871. In 1875, the army was called in to crush a strike of workers at the Gotthard tunnel. Four workers were killed and 13 were severely wounded. Paragraph 19 of the revised constitution of 1874 extended the definition of the federal