When Gerhard VI Graf von Holstein-Rendsburg, Herzog von Schleswig was born in 1367, in Itzehoe, Steinburg, Schleswig-Holstein, Germany, his father, Graf Heinrich II von Holstein-Rendsburg, was 50 and his mother, Ingeborg von Mecklenburg-Schwerin, was 24. He married Katherina Elisabeth von Braunschweig-Lüneburg in 1395, in Braunschweig, Braunschweig, Niedersachsen, Germany. They were the parents of at least 3 sons and 2 daughters. He died on 4 August 1404, in Dithmarschen, Dithmarschen, Schleswig-Holstein, Germany, at the age of 37, and was buried in Itzehoe, Steinburg, Schleswig-Holstein, Germany.