The Valais is one of the 26 cantons of Switzerland, situated in the southwestern part of the country, around the valley of the Rhône from its headwaters to Lake Geneva, separating the Pennine Alps from the Bernese Alps. The canton is simultaneously one of the driest regions of Switzerland in its central Rhône valley and among the wettest, having large amounts of snow and rain up on the highest peaks found in Switzerland. The canton of Valais is widely known for the Matterhorn and resort towns such as Saas Fee, Verbier, and Zermatt. It is composed of 13 districts (hence the 13 stars on the flag) and its capital is Sion.
The Romans called the upper Rhône valley Vallis Poenina. The Vallis Poenina was won by the Romans after a great fight at Octodurus (Martigny) in 57 B.C., and was so thoroughly Romanized that both the Celtic original inhabitants and the Germanic Burgundian invaders of the 5th century, became romance language-speaking peoples. According to a tradition which can be traced back to the middle of the 8th century, the Theban legion was martyred at Agaunum (now Saint Maurice) about 285 or 302. From 888 onwards the lands were part of the kingdom of Jurane Burgundy.
About the middle of the 13th century, the large communities (Zenden or tithings) began to develop independence and grow in power. The name Zenden or tithings probably came from a very ancient division of the bishop's manors for administrative and judicial purposes. In the same century the upper part of the valley was colonized by Germans from Hasli in the Canton of Bern. The locals became German speaking, though many Romance local names still remain. In 1354 the liberties of several of the seven Zenden (Sion, Sierre, Leuk, Raron, Visp, Brig and Conches) were confirmed by the Emperor Charles IV.
By the late 14th century, the counts of Savoy acquired the bishopric of Sion. The Zenden resisted his attempts to gather both spiritual and secular power in the valley. In 1375-76, Zenden forces crushed the army of the house of La Tour-Chatillon, and in 1388 utterly defeated the forces of the bishop, the count and his nobles at Visp. The German-speaking Zenden spread further into the valley. Starting in 1384 the Morge stream (a little below Sion) was recognized as the boundary between Savoyard, French speaking Lower Valais and German speaking episcopal Upper Valais.
During the Raron affair rebellion in 1414 to 1420, some cantons of the Swiss Confederation took sides in the Valais. Lucerne, Uri and Unterwalden supported the Upper Valais rebels, while Bern supported the noble Raron family. The uprising was successful in driving out the Rarons, and almost brought the Confederation to civil war.
The Valais resisted the Protestant Reformation, remaining faithful to the Roman Catholic Church. In 1628 the Valais became a republic, the République des Sept Dizains/Republik der Sieben Zehenden, under the guidance of the prince-bishop of Sion and the bailli. The bishop remained in power until 1798 when Napoleon's troops invaded the Valais and declared a Revolutionary République du Valais (March 16) which was swiftly incorporated (May 1) into the Helvetic Republic until 1802 when it became the separate Rhodanic Republic. In 1810 the Rhodanic Republic was annexed by Napoleonic France as the département of Simplon. Independence was restored in 1813, and on August 4, 1815 the Valais finally entered the Swiss confederation as a canton. In 1845, the Valais joined the Catholic separate league (Sonderbund) which led to what is called the Sonderbund War. 99,000 Swiss Federal troops under General Henri Dufour were faced by 79,000 Separatists, but in the end the Valais chose not to fight.