Landgraviate of Hesse

The Landgraviate of Hesse (Landgrafschaft Hessen) was a Principality of the Holy Roman Empire. It existed as a unity from 1264 to 1567, when it was divided between the sons of late Landgrave Philip I.

History
In the early Middle Ages the Hessengau territory (named after the Germanic Chatti tribes) formed the northern parts of the German stem duchy of Franconia along with the adjacent Lahngau. Upon the extinction of the ducal Conradines, these Rhenish Franconian counties were gradually acquired by Landgrave Louis I of Thuringia and his successors.

After the War of the Thuringian Succession upon the death of Landgrave Henry Raspe in 1247, his niece Duchess Sophia of Brabant secured the Hessian possessions for her minor son Henry the Child, who would become the first Landgrave of Hesse and founder of the House of Hesse in 1246. The remaining Thuringian landgraviate fell to the Wettin margrave Henry III of Meissen. Henry I of Hesse was raised to princely status by King Adolf of Germany in 1292.

From 1308 to 1311 and again from 1458 the landgraviate was divided in Upper Hesse and Lower Hesse until its re-unification under Landgrave William II in 1500. The Landgraviate rose to primary importance under William's son Landgrave Philip I also called Philip the Magnanimous who embraced Protestantism upon the 1526 Synod of Homberg and thereafter took steps to create a protective alliance of Protestant princes and powers against the Catholic emperor Charles V. Upon the death of Philip I in 1567, the Landgraviate was divided between his sons from his first marriage, which decisively enfeebled its importance: The Hessian territories were not re-united until the formation of Greater Hesse (though without Rhenish Hesse) as part of Allied-occupied Germany in 1945.
 * Hesse-Kassel (or Hesse-Cassel, Electorate of Hesse from 1803, incorporated into the Prussian province of Hesse-Nassau in 1866) to William IV
 * Hesse-Marburg (line extinct in 1604, incorporated into Hesse-Kassel and Hesse-Darmstadt) to Louis IV
 * Hesse-Rheinfels (line extinct in 1583, incorporated into Hesse-Kassel) to Philip II
 * Hesse-Darmstadt (Grand Duchy of Hesse from 1806, People's State of Hesse from 1918) to George I