Imperial County in southeastern Germany until 1248, which, until 1132, had been called Diessen. Diessen is a town at the southwestern corner of Ammersee, a lake southwest of Munich, while Andechs was a castle overlooking the lake from the east.
The Counts of Andechs, who may well have been descended from the Luitpoldings, the Dukes of Bavaria in the first half of the 10th century, built up a considerable, though scattered, territory. From the Bishops of Brixen they held part of the Innertal, including Innsbrück, and this was linked to their lands around Ammersee. They also held the Pustertal on the further side of the Alps as a fief from the Bishop. In eastern Bavaria they acquired part of the inheritance of the Counts of Formbach: an arc of territory to the west of Passau, lands which now straddle the boundary between Austria and Germany. Way to the north, in eastern Franconia, they obtained part of the inheritance of the Margraves of Schweinfurt, including the districts around Kulmbach and Bayreuth, after 1157. In 1173 Count Berthold became Margrave of Istria, on the borders of the Empire and the shores of the Adriatic. About 1183 the Count-Margrave became Duke of Meran (meaning, Duke of the sea, i.e. the Adriatic shores in Istria). It was merely a title, and was probably compensation for not succeeding the deposed Henry the Lion as Duke of Bavaria in 1180, for the Count of Andechs was more powerful within the Empire than the Wittelsbach Count who had been preferred to him as Duke.
The family were still enormously powerful. Of the sons of Duke Berthold, who died in 1204, the Duke of Meran married the heiress of the County Palatine of Burgundy, and thus the family gained a presence in the Jura, the second son was Margrave of Istria, while two others were churchmen, the Bishop of Bamberg and the Patriarch of Aquilaea. Of the daughters, one was Duchess of Silesia, another Queen of Hungary, and a third, Agnes, was the third wife of Philip Augustus, King of France. Her status was dubious however, because Philip’s second wife was still alive and was indeed to long out-live both her husband and Agnes.
The fortunes of the family changed in 1208 when they were allied with Otto of Wittlesbach, the Count Palatine of Bavaria, against his cousin, the Duke of Bavaria. In that year Otto murdered Philip, the German King, and the House of Andechs shared in the disgrace. Their fortunes had only partially recovered when the last lay male died in 1248, and their lands were divided up. In Franconia, the Bishop of Bamberg, the Counts of Orlamünde and Truhendingen, and the Burgrave of Nuremberg gained; in the Tirol, the Counts of Görz were the eventual beneficiaries; whilst in Bavaria it was the Duke who absorbed the Andechs lands.