In 1385, Landgrave Balthasar of Thuringia moved to town and in 1386 he built a castle. In 1433, the town passed back to the Landgraviate of Hesse. Philip I, Landgrave of Hesse, William IV, Landgrave of Hesse-Kassel and Maurice, Landgrave of Hesse-Kassel expanded the castle into a palatial residence. From 1627 to 1632, this was Maurice's “old man’s seat” after he had abdicated, and from 1632 to 1655, Landgrave Frederick of Hesse-Eschwege, a sideline in the so-called "Rotenburger Quart" of the house of Hesse-Kassel, was resident here, although he did not actually live in the town until some time after 1646. In the Thirty Years' War, Eschwege was sacked and widely laid waste by fire in 1637 by Imperial Croats under General Johann von Götzen. After Frederick's death in 1655, his (part-)landgraviate passed to his brother Ernst of Hesse-Rheinfels. After 1731, his grandson, Christian of Hesse-Wanfried transferred the residence of the Landgraviate of Hesse-Wanfried to Eschwege. After the Hesse-Wanfried male line died out in 1755, the landgraviate passed to the Hesse-Rotenburg line. Once their male line also died out in 1834, the whole "Quart" passed back to the main house of Hesse-Kassel.