Region in the southwestern corner of Germany, once a Frankish county. The name is used particularly for the Habsburg possessions in that region; it was also the name of a short-lived Duchy, 1801-5. The name comes from Breisach, which stands on the Rhine west of Freiburg, where a fortifiable hill, called Mons Brisiacus by the Romans, dominates the plain. The Frankish Gau was bordered by the Rhine in the south and west, the small river Bleich in the north, and the western slopes of the southern Black Forest in the east.
In the 11th century the most powerful Counts in the region split into two branches. The senior line held land in the south of the Breisgau around Sausenberg, but the centre of its power became Baden, well north of the Breisgau. The region around Sausenberg, and also the district around Hachberg, to the north of the original Breisgau, were held by a branch of the family from the late 12th century.
That branch partitioned its lands in 1297 but they all eventually came back to the Margraves of Baden: Hachberg in 1415, and Sausenberg in 1503. From 1515 the Breisgau lands of Baden, together with Hachberg, were held by the branch of Baden-Durlach, which reunited all the lands of the family in 1771.
The junior line of the 11th century Counts were for a time even more powerful. By the end of the century they had become the Dukes of Zähringen (Zähringen was a castle near the city of Freiburg-im-Breisgau); they founded Freiburg and developed much of the Black Forest, only a part of which was in the old Frankish district, and also much of western Switzerland. On their extinction in the male line in 1218, most of the Breisgau lands were inherited by the Counts of Urach, and held by the Urach-Freiburg branch of that family. In the 14th century the Counts of Urach-Freiburg became financially overstretched.
The result was that the Habsburgs, who held lands in nearby Alsace and who had inherited from the Counts of Kiburg many of the Zähringer lands in Switzerland, acquired much of the Urach property in the Breisgau, e.g. Breisach in 1330-1 and Freiburg in 1368, being also granted the title of Landgrave in Breisgau by the Emperor Charles IV about the same time. (Those lands still retained in the Breisgau by the Urach family were eventually inherited by the Margraves of Baden in 1457).
To the south and east, the Habsburgs had long held lands on both banks of the river Rhine above Basle (the Waldstädte), and had acquired the Fricktal south of the Rhine (now in northwestern Switzerland) and lands in the eastern Black forest around Villingen. These territories were joined together to form an administrative unit within the wider territory of Vorderösterreich (the western lands from Tirol to Alsace), which was known as Breisgau und auf dem Schwarzwald (Breisgau and on the Black Forest).
The Habsburg lands in the Breisgau might have been permanently lost by the Habsburgs in 1469, when Sigismund of Tirol, who held the western lands, pledged several of them to Charles the Rash, Duke of Burgundy. As Sigismund was a spendthrift Charles had an excellent chance of turning a temporary pledge into a permanent gain. But the Alsatian cities, the Swiss and the French King, all opponents of the expansion of Burgundy, ensured that enough money flowed Sigismund’s way for him to redeem the pledge in 1474.
In the wars involving France and Austria, the lands of the Breisgau were intermittently occupied by the French, though they were usually returned at war’s end. Breisach however, with its strategic hill, was retained by France at the end of the Thirty Years’ War in 1648, the same settlement as saw the Habsburg lands in Alsace pass permanently to France. By the Treaty of Nijmegen, 1678-9, Freiburg im Breisgau and surrounding territory were also transferred to France. The Peace of Ryswick in 1697 returned both Breisach and Freiburg to Austria.
The revolutionary wars of the 1790s saw the Austrian Breisgau occupied by French troops again, and in the Peace of Campo Formio in 1797 the Emperor promised to bestow the Breisgau gains on the Duke of Modena as compensation for that prince’s loss of his lands to France. The Emperor managed to evade his commitment until 1801, when Duke Ercole III became Duke of Breisgau. His Duchy also included the Ortenau, a former Austrian territory east of the Rhine near Strasbourg. It was not a complete loss for Austria, since Ercole was succeeded in 1803 by his son-in-law, the Archduke Ferdinand, uncle of the Emperor. Austria‘s defeat at Austerlitz in 1805 lost Ferdinand his Duchy, the great bulk of which became part of Baden, thus uniting under one ruler the ancient district of the Breisgau. In 1810 Baden also acquired the small part of Ferdinand’s Duchy previously allocated to Württemberg.