In 878 the
East Frankish king
Carloman of Bavaria dedicated the
Treffen estates around
Lake Ossiach to the Benedictine monastery of
Ötting. In the late 10th century the lands passed to the
Bishops of Passau and later to Emperor
Henry II, who conferred them to a certain Count Ozi, affiliated with the Styrian
Otakar dynasty and father of Patriarch
Poppo of Aquileia. A church probably already existed at Ossiach, when Count Ozi about 1024 established the Benedictine abbey, the first in the medieval
Duchy of Carinthia. The first monks probably descended from
Niederaltaich Abbey in
Bavaria. Ozi's son Poppo succeeded in removing the proprietary monastery from the influence of the
Salzburg archbishops and to affiliate it with the
Patriarchate of Aquileia, confirmed by Emperor
Conrad II in 1028. Upon the extinction of the Styrian Otakars in 1192, the
Vogtei of Ossiach according to the
Georgenberg Pact passed to the Austrian
House of Babenberg. In 1282 it finally fell to the
Habsburgs. The
Romanesque church itself was first mentioned in 1215, built on the groundplan of a
basilica, with the tower above the
crossing. Restored in a
Late Gothic style after a fire in 1484, the abbey, a member of the Benedictine
Salzburg Congregation from 1641, was extensively altered in the
Baroque period, including stucco decoration of the
Wessobrunner School. Ossiach Abbey was dissolved by order of Emperor
Joseph II in 1783, after which the buildings were used as a barracks. In 1816 the premises were largely demolished. Between 1872 and 1915 the few remaining buildings were again used as a barracks and as stabling. Since 1995 the premises have been owned by the administration of Carinthia. The church since the dissolution has served the local parish. Two
stained glass windows were donated by
Karl May in 1905, though according to recent research the popular writer had probably never visited Ossiach. ==Bolesław legend==