Most consider 1291 to be the date Switzerland became a nation. That year, the three cantons of Uri, Unterwalden and Schwyz, agreed to stand together against outside judges and aggressors.
Progressively over the years Switzerland expanded from these three cantons, to 25, when Geneva joined in 1815. Switzerland would wait more than 160 years to gain its 26th canton.
In 1963, separatists blew up a branch of the Bern Cantonal Bank in Delémont. This incident followed the burning of three farms by separatists. Growing numbers from the French-speaking Jura region of the largely German-speaking canton of Bern, were calling for self determination and their own canton.
In 1974, the question of separation was put to the jurassien people in a referendum. The vote saw 52% of jurassiens vote in favour of breaking away, but with only three out of the Jura region’s seven districts delivering a majority in favour.
Eventually the three districts in favour of separation, put together a state constitution, and on 24 September 1978, the Swiss public voted the new canton, the République et Canton du Jura, into being from 1 January 1979, bringing Switzerland’s canton count to 26 – 3.8 million, 82% of voters voted in favour of the move.
Historic dates in the creation of the Canton of Jura (in French) – Take a 5 minute French test now
RTS documentary on the separatist group les “Beliers” (in French)
Results of 1978 referendum to create the Canton of Jura (French/German/Italian)