In 1192 he held captive Richard the Lionheart, King of England, at Dürnstein Castle.

Hadmar II also erected from 1201 to 1208 the city of Weitra.

Because of the creation of this city, they are sometimes referred to in documents as "Lords of Kuenring-Weitra".

Hadmar is mentioned in the Stifterbuch (Liber fundatorum; the cartulary of Zwettl Abbey[a]) as second founder (secundus fundator) of the monastery.

Hadmar's sister Gisela (d. after 1192) was married to Leutwin of Sunnberg.