Kunigunde of Eisenberg was born circa 1245 as the daughter of Count Otto of Eisenberg and his wife Anna of Kottwotz.
She acted as a lady-in-waiting to Margaret of Sicily, daughter of Frederick II, Holy Roman Emperor by his third wife, Isabella of England and wife of Albert II, Margrave of Meissen, Landgrave of Thuringia and Count Palatine of Saxony.
The marriage of Albert and Margaret began well, and the couple had five children together. We don’t know how the marriage turned sour, but Albert soon began an affair with Kunigunde, and they had two children together. Kunigunde must have envied Margaret’s position at court, and with Albert’s knowledge, it is said that Kunigunde attempted to poison Margaret several times, so that she could take her place at court. Margaret realised what was going on and became very afraid. Margaret fled the court in the middle of the night of 24 June 1270. She would die just six weeks later in Frankfurt am Main in a convent of an unknown cause. She was supposedly buried there, but her grave was not found during excavations after the Second World War.
Kunigunde and Albert were now free to marry and so they did in 1272. She concealed her son under her dress during the ceremony as this was supposed to secure for him the privilege of legitimacy. The marriage was not well received, and his legitimate sons by Margaret were estranged from him. This led to several military expeditions by his sons against him.
The hostilities only ended when Kunigunde died sometime before 31 May 1286. She was buried in the St. Catherine monastery in Eisenach.