Wilhelm IV (Landgrass of Hesse-Kassel)

Wilhelm is the eldest son of the Hessian landgraph Philip I and his wife Christina of Saxony .

In 1547 , when his father was captured after the defeat of the Protestants near Mülberg , the 15-year-old boy was forced to assume the functions of ruler. A few years later, in 1551 , he returned power to his returning father.

After the death of Philip in 1567, the Hessian Landgrafism was divided into four parts between his sons. Since Wilhelm got Kassel with the adjacent northern regions of landgrafism, he is considered the founder of the Kassel line of the Hessian house. On the other hand, the partition of Hesse meant the loss of political influence, and William was forced to pay more attention to domestic politics, including the consistent implementation of the Lutheran Reformation in his landgrafism.

In the years 1570-1580 - after the suppression of the birth of Plesse (the youngest line, German Plessen ), Hoya , Dipholz ( German von Diepholz ) and Henneberg - Wilhelm IV managed to expand the territory subject to him. Thus, from the Henneberg inheritance, Wilhelm obtained possession of Schmalkalden, making the city ​​of the same name his summer residence and where, at his request, the castle named in his honor was built Wilhelmsburg .

After the death of his brother Philip, Wilhelm also inherited most of the former county of Katzenelbogen .

Wilhelm patronized science and art. In 1561, he built the first astronomical observatory in Europe in Kassel. Among the employees of the observatory was one of the first supporters of the heliocentric system of the world, Christopher Rothman , for some time Tycho Brahe worked there. Part of the astronomical studies of William IV was published by Snellius under the title Coeli et siderum observationes (Leid., 1618). An even larger part is stored as a manuscript in the Kassel library.

William IV died in 1592 , he was succeeded by his son Moritz.

In 1566, Wilhelm married Sabine of Württemberg , was born in marriage:

• Anna Maria (1567-1626), married to Count Ludwig II of Nassau-Saarbrücken (1565-1627)
• Gedwig (1569-1644), married to Count Ernst Holstein-Schaumburg (1569-1622)
• Agnes (1569-1569)
• Sofia (1571-1616)
• Moritz (1572-1632), Landgrave of Hesse-Kassel, married to Countess Agness Solms-Laubach (1578-1602), then Countess Julian of Nassau-Dillenburg (1587-1643)
• Sabina (1573-1573)
• Sidonia (1574-1575)
• Christian (1575-1578)
• Elizabeth (1577-1578)
• Cristina (1578–1658), married to Duke Johann Ernst of Saxe-Eisenach (1566–1638)
• Juliana (1581-1581)

In honor of William IV in 1935, a crater on the visible side of the moon was named.