The first document in which the settlement of Ersheim is mentioned is the Lorsch codex in an endowment dated 773 (Lorsch Documents, no. 2624). This settlement, which in 1023 under the name of Erasam belonged to the property of a monastery affiliated to Lorsch, St Michael's on Heiligenberg near Heidelberg, was one of the oldest in the Neckar valley. Whereas almost the whole of the surrounding area came into the possession of the diocese of Worms in the 11th century, Ersheim together with the nearby village of Ramsau downriver on the right bank remained an exclave of Lorsch. From here several villages were founded in forest clearings from the 12th century onward, among them Weidenau, Unter-Hainbrunn, Igelsbach and Krautlach, but they were largely abandoned again afterwards.
The actual town of Hirschhorn southwest of Ersheim on the right bank of the Neckar derives its name from its founders, the Lords of Hirschhorn, whose coat of arms shows a stag's antler. The first Lord of Hirschhorn was probably a son of a knight of Steinach. Hirschhorn Castle (Burg Hirschhorn) was built about 1250/60 on land given as a fief by Lorsch Abbey, which since 1232 was in the possession of the Archbishop of Mainz. Engelhard I (1329 - 61) increased his influence and his dominions considerably through Imperial fiefdoms and land mortgaged to him in return for loans. His son, Engelhard II, waged various feuds and was placed under the Imperial ban; Engelhard II's sons, however, managed to enlarge the family's estates again.
Hirschhorn (Hirtzhorn) was surrounded by a town wall after the brothers Hans V, Albrecht and Eberhard of Hirschhorn had received its town charter from King Wenceslaus in 1391. When Elector Palatine Ruprecht III was elected King in 1400, Hans V of Hirschhorn was employed in Imperial service as an adviser, diplomat, and financier. His diplomatic missions also took him to the English court. King Henry V of England held Hans in such high esteem that he
