The occasion was probably the penance imposed on them for the total destruction of the city Fritzlar and the desecration of the local collegiate church two years earlier.
Grüningen remained until 1251 Landmeister in Livonia, briefly interrupted 1241-1242 by an interim office of Andreas von Felben.
Grüningen completed the conquest of Kurland and built a number of castles, including Goldingen (Kuldīga)[3] and Amboten (Embūte).
In December 1254, he concluded in the name of the Order a comparison with the Archbishop of Riga and the bishops of Bishopric of Ösel–Wiek, Courland and Dorpat, in which they are concerned about their respective claims to power in Livonia agreed.
During the campaign of the king Ottokar II of Bohemia against the Prussians in Samland in the spring of 1255, Dietrich von Grüningen joined him in Elbing with a squad of knights from Kulm and the Warmia; Otto III, Margrave of Brandenburg.