An obscure minor noble family in Swabia, the Zähringen dynasty owed their rise to power to the support they gave to the cause of the nobility in its long running dispute with Emperor Heinrich IV King of Germany in the last decades of the 11th century. The ducal branch acquired the family's Swabian possessions, maintained the title "duke" after the head of the family ceased to be Duke of Swabia and eventually applied it to the imperial fief of Zähringen which it held directly from the crown. This family provides one of the earliest examples of what Otto von Freising called "an empty title"[710], unlike a duchy in the ancient sense despite being recognised by the imperial government. The Zähringer increased their power west of the Rhine when Konrad von Zähringen acquired the rectorship of Burgundy in 1127. They consolidated their position in the Black Forest south of the Kinzigtal by transferring the family monastery of Weilheim to St Peter in 1093, establishing Alpirsbach in 1095[711], holding the advocacies of the monasteries of Gengenbach, Schuttern and Stein am Rhein, and acquiring those of St Georgen (in 1114) and St Blasien (in 1125)[712]. They dominated the other two independent baronial families in the region between the Kinzig valley and the upper Rhine, the Markgrafen von Breisgau and the Herren von Schwarzenberg (advocates of Waldkirch)[713]. Their dominance was challenged by the Hohenburg family in the Dreisamtal, when Bruno von Hohenburg (later Bishop of Strasbourg) founded the monastery of St Märgen in 1118, accepted by the Zähringer family under a settlement reached by arbitration in 1121[714]. After gaining control of the road from the Breisgau, they founded the towns of Freiburg and Villingen at each end, as well as Offenburg, to consolidate their position[715]. They acquired Breisach in 1198[716]. The Dukes of Zähringen achieved internal administrative authority and territorial unity due to the lack of serious rivals, their ducal title (which attracted more prestige and authority than if they had been mere counts), encouraging colonisation into the uninhabited Black Forest areas, and fostering commercial development by granting freedoms to the citizens of the towns they founded such as Freiburg. Their land became one of the earliest "new" territorial states in Germany which did not trace its development to evolution from one of the ancient tribal duchies. Their unified state did not survive the extinction of the dynasty in 1218, as the lands on the eastern bank of the Rhine were inherited by the Grafen von Urach, while the Burgundian and Swiss properties went to the Grafen von Kiburg, and on the extinction of the latter in 1263 to the Grafen von Habsburg, a fragmentation which mirrored the process experienced in most parts of medieval Germany.
The Genealogia Zaringorum[717] was written at the monastery of St Peter in the Black Forest, early in the 13th century judging by its recording the death of the youngest son of Konrad Duke of Zähringen. It is accompanied by a Continuatio, probably written just over a century later as it ends with a marriage dated elsewhere to before 1318. BERTHOLD, son of BERTHOLD I "the Bearded" Duke of Carinthia & his first wife Richwara of Swabia [Babenberg] ([1050]-12 Apr 1111, bur St Peter im Schwarzwald). The Genealogia Zaringorum names "Berchtoldus" son of "Berchtoldus Cum-barba", referring to him first among the brothers, specifying that he was buried at St Peter in 1111[718]. The Gesta Friderici of Otto of Freising records that "Berhtolfus de castro Zaringen" usurped the duchy of Swabia after his father-in-law died[719], although this does not appear to have happened until after the death of his brother-in-law. Berthold took over the rights and estates of his brother-in-law Berthold von Rheinfelden in Swabia and Burgundy on the latter's death in 1090[720]. He was installed as BERTHOLD II Duke of Swabia in 1092 by Emperor Heinrich IV. He was unable to obtain effective control and in 1098 renounced his claims to Swabia[721] in favour of Friedrich [I] von Staufen, although he retained the title of duke and was enfeoffed with imperial estates in and around Zürich[722]. Mayer says that Berthold II retained "both the Reichsvogtei in Zürich and the title duke"[723]. He was installed in 1092 as BERTHOLD II Duke of Carinthia, in opposition to Duke Heinrich II [Eppenstein]. Together with Duke Welf IV, he organised an oath of peace at Ulm in 1093, valid for Swabia and later extended to Bavaria, to strengthen opposition to the Salian monarchy[724]. He founded Kloster St Peter in Schwarzwald in 1093. He adopted the title Herzog von Zähringen from 1100, named after his family castle. The Gesta Friderici of Otto of Freising comments that Berthold held "the empty title of duke" without the substance[725]. The necrology of St Peter im Schwarzwald records the death "II Id Apr" of "Berchtoldus 2 dux de Zaeringen qui primus huius loci fundator extitit 1111"[726].
m ([1077/79]) AGNES von Rheinfelden, daughter of RUDOLF von Rheinfelden Duke of Swabia [later King of Germany] & his second wife Adelaide de Savoie (-19 Dec 1111). The Genealogia Zaringorum names "Agnes filia regis Rudolfi Arulacensis" wife of "Berchtoldus", specifying that she was buried with her husband at St Peter in 1111[727]. The Annales of Berthold record the marriage in 1079 of "Berhtoldus marchio, ducis Berhtoldi filius, adolescens" and "Agnetem, Roudolfi regis filiam"[728]. The Gesta Friderici of Otto of Freising records that "Berhtolfus de castro Zaringen" married "Radolfi filia" but does not name her[729]. The necrology of St Peter im Schwarzwald records the death "XIV Kal Jan" of "Agnes uxor ducis Berchtoldi et filia Ruodolfi regis de Arle"[730].
Herzog Berthold & his wife had nine children