AARGAU Argovie(Fr); Argovia.
(1) District in the East Frankish Kingdom, mostly between the Rivers Aare and Reuss, now in northern Switzerland; (2) a Canton of the Helvetic Republic, lying west of the lowest reaches of the Aare; and (3) since 1803 a Canton (AG) in the north of the Swiss Confederation, on both banks of the Aare. The River Aare is the largest river solely within Switzerland and actually brings more water to its confluence with the Rhine than the Rhine itself. Its German name is Aar, but, although the river belongs to German-speaking Switzerland, the French spelling is normal.
When the Carolingian lands were partitioned among the sons of Louis the Pious in 843, the River Aare formed the border between the lands of Louis the German and the Middle Kingdom of his brother, the Emperor Lothar. The Aargau was thus the southwesternmost corner of the East Frankish or German Kingdom until Rudolf II of Burgundy acquired much of it, c.922, as a result of his marriage with the daughter of the Duke of Swabia, with whom he had been in dispute.
The Aargau later fragmented. The southern half, the Obere Aargau, is today divided between the Cantons of Bern, Lucerne and Obwalden – the northeastern corner of Bern is still called Oberaargau.
In the northern half, the Untere Aargau, the Counts of Lenzburg, whose castle lay between the Aare and the Reuss, were powerful. They also held land between the Aare and the Rhine, and a branch of their family held territory across the Aare and Reuss in the German Kingdom. When they died out in 1173, part of their lands came to the Counts of Habsburg – Habsburg was a castle not far from the confluence of the Aare and the Reuss – and more of the inheritance, particularly east of the Aare/Reuss line, became Habsburg in the 1260s. The name of Aargau was now associated with these territories, only part of which had been in the original district.
The Habsburgs were driven out by the Swiss in 1415, after Frederick, the Habsburg Count of Tirol, had fallen foul of the Emperor Sigismund at the Council of Constance through helping Pope John XXIII, one of three rival Popes, to escape. The lands west of the Aare/Reuss line were made subject to Bern; those to the east were held jointly by several of the members of the Swiss Confederation, in two groups of territories, Baden and the Freie Ämter.
When the Helvetic Confederation was formed in 1798, the Bernese Aargau west of the Aare became the Canton of Aargau while the subject lands east of the river became the Canton of Baden, which also included the lands of the secularised Abbey of Muri. The Helvetic Confederation was abandoned in 1803 but there was no return in the new Swiss Confederation to the subjection of districts like the Aargau to members of the Confederation. Instead a new Canton of Aargau was formed by uniting the two Helvetic Cantons of Aargau and Baden, and adding the Fricktal and the towns of Rheinfelden and Laufenburg. These lay west of the confluence of the Aare and Rhine, and had been held by the Habsburgs until 1801, the last of their lands south of the Rhine.
The language of Aargau is German, and it has a Protestant majority, though there is a significant Catholic population in the southeast, where the Abbey of Muri had been independent until 1798 while the Freie Ämter had been ruled exclusively by Protestant members of the Confederation only from 1712. Aargau is unmountainous, 10th in area in the Confederation, but 4th in population. It is 16th in precedence of the cantons and 19th of the members of the Confederation. Its capital is Aarau.
It was in Aarau that the Helvetic Republic was proclaimed in 1798, a significant act as it had hitherto been subject to Bern, though the hope of the town that it would be the capital of the new Republic was disappointed. Lucerne was chosen instead.