 The Landgraviate of Hesse-Darmstadt came into existence in 1567, when George, youngest of the four sons of Landgrave Philip I "the Magnanimous", received the Hessian lands in the former upper County of Katzenelnbogen.His eldest brother William IV received the Landgraviate of Hesse-Kassel, while the second son Louis IV obtained Hesse-Marburg, and the third Philipp II became Landgrave of Hesse-Rheinfels.The Hesse-Rheinfels line became extinct on Philip's death in 1583.