Gerhard VI was born around 1367, the son of Count Henry II from the Rendsburg line of the House of Schauenburg and Ingeborg of Mecklenburg. After the death, in 1381 or 1384, of his father, who had ruled jointly with Gerhard"s uncle Nicholas (Claus), Gerhard and his younger brother Albert II entered into the joint government for their late father.
In 1403 Gerhard regained Segeberg by way of reversion upon Albert"s death in action against Ditmarsh, thus ruling almost the whole of Holstein except of Holstein-Pinneberg. The Duchy of Schleswig and the County of Holstein-Rendsburg were then under one ruler. He fell in the Battle on the Hamme on 4 August 1404 during another attempt to subjugate Ditmarsh.
In 1391 Gerhard married Catherine Elisabeth of Brunswick-Lüneburg, daughter of Magnus II of Brunswick-Lüneburg.
They had the following children:
Henry IV (b 1397. Doctorate 1427), Duke of Schleswig, Count of Holstein
Ingeborg (b 1398.
Doctorate 1465)
Helvig (b ca 1400. Doctorate ca 1436), married Dietrich of Oldenburg, mother of Christian I, King of Denmark.
Adolphus VIII (b 1401.
Doctorate 1459), Duke of Schleswig, Count of Holstein
Gerhard VII (b 1404. Doctorate 1433), Duke of Schleswig, Count of Holstein.
