"Geronem marchionem" is named in the Annalista Saxo, which also records his parentage. A boy [puer] in 980, which provides the basis for estimating his birth date range.
Graf im Hassegau 992. Markgraf [der Lausitz] 993. "…Gero comes…" was among the witnesses of the charter dated 1013 under which "Henricus…imperator augustus" renewed his 1007 judgment concerning a dispute between Willigis Archbishop of Mainz and Bernward Bishop of Hildesheim, although it is not certain that this is the same person as he is described as "comes" rather than "marchio".
Thietmar records the death of "Markgraf Gero" in battle against the Poles, dated to 1015, and his burial at Nienburg. 1
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