- Didrik den Lykkelige, Greve af Oldenburg og Fader til den danske Konge Christian I. Ved D.?s Tiltrædelse af Regeringen var hans fædrene Fyrsteland delt i adskillige Dele; men D. arvede baade en Broder o. fl. Fættere og samlede hele Grevskabet paa sin Haand, ja forenede dermed Delmenhorst; heraf hans Tilnavn.
I andet Ægteskab var D. gift med Hedvig, en Datter af Grev Gerhard VI af Holsten, som i tredie Led nedstammede fra Erik Klipping?s Datter Richiza. Hun fødte ham tre Sønner, hvoraf Christian var den ældste; inden Børnene var blevet voksne, døde baade Moderen (1436) og Faderen (1440). Christian og hans Brødre blev derefter opfostrede hos deres Morbroder, Hertug Adolf af Slesvig, og dennes
Indflydelse mere end sin Nedstamning fra en dansk Kongedatter skyldte han sit Valg til Danmarks Konge 1448. Kr. E.
Dietrich II 'the Fortunate', Graf von Oldenburg, Graf von Delmenhorst, was born about 1398, the son of Christian V, Graf von Oldenburg, and Gräfin Agnes von Honstein. He was called 'Fortunatus' (the Fortunate) as he was able to secure Delmenhorst for his branch of the Oldenburgs.
Dietrich was the grandson of Gräfin Ingeburg von Holstein-Segeberg, who had married Konrad I. After the death in 1350 of her only brother Gerhard V, Ingeburg and her issue were the heirs of her own grandmother Princess Ingeborg Valdemarsdotter of Sweden, the eldest daughter of Erik IV-VI 'Plovpenning', king of Denmark and Jutta von Sachsen. Since other legitimate descent from King Valdemar apparently was extinct by this time, Dietrich was considered the heir general of kings Valdemar of Sweden and Erik IV-VI of Denmark. Dietrich succeeded his father as head of the House of Oldenburg in 1423. As a child he had been married (for reasons of succession and uniting the hereditary fiefs) to a distant cousin Adelheid von Oldenburg-Delmenhorst (who is said to have died already in 1404) daughter of Otto IV, Graf von Oldenburg-Delmenhorst.
On 23 November 1423 he married Gräfin Hedwig von Holstein, widow of Balthasar, Fürst von Werle, and daughter of the murdered Gerhard VI, Graf von Holstein, Herzog von Schleswig, and Duchess Katharina/Elisabeth of Brunswick-Lüneburg. Dietrich and Heilwig had three surviving sons and a daughter. Their sons Christian I and Gerhard VI and daughter Adelheid would have progeny.
Dietrich's second marriage strengthened his interest in Scandinavian monarchies, since Heilwig was a descendant of Erik IV-VI 'Plovpenning', king of Denmark, Håkon V Magnusson, king of Norway, and Magnus Ladulas, king in Sweden.
Dietrich is said to have been a rival claimant to the crowns of Sweden and Denmark during the reign of Erik X, king of Denmark, Sweden and Norway, whose succession was through Christopher I of Denmark, the younger brother of the murdered Erik IV-VI 'Plovpenning', and through Magnus Ladulas of Sweden, younger brother of the deposed King Valdemar Birgersson.
Dietrich died on 14 February 1440. On the death in 1448 of Christopher III, king of Denmark, Norway and Sweden, the crowns were offered to Adolf VIII, Graf von Holstein, Herzog von Schleswig. However he declined (possibly because he had no surviving issue), and he suggested Christian, the son of his sister Heilwig and her husband Dietrich; Christian became Christian I, king of Denmark and Norway.