Otto I, Landgrave of Hesse

Otto I of Hesse (c. 1272 – 17 January 1328) was Landgrave of Hesse from 1308 until his death.

Otto I
Landgrave of Hesse
Born	1272 Marburg
Died	17 January 1328 Kassel
Noble family	House of Hesse
Spouse(s)	Adelheid of Ravensberg
Issue	Henry II the Iron Otto, Archbishop of Magdeburg Louis the Junker Hermann I the Elder Elisabeth
Father	Henry I, Landgrave of Hesse
Mother	Adelheid of Brunswick-Lüneburg

Otto was born in Marburg, a son of Henry I, Landgrave of Hesse and his first wife Adelheid of Brunswick-Lunenburg. Following the death of his father in 1308, he inherited Upper Hesse, the "Land on the Lahn", which included Marburg, Giessen, Grünberg and Alsfeld. After his half-brother John died in 1311, he also became landgrave of Lower Hesse. This included the area below the Fulda, Eder, Schwalm, Werra, and the upper reaches of the Weser, with the residence of Kassel, as well as the towns of Homberg (Efze), Melsungen, and Rotenburg an der Fulda.

After Otto inherited the whole Landgraviate, he resided alternately in Kassel and Marburg. Otto had a long conflict with the Archbishop of Mainz, Matthias von Bucheck. In 1324 Mainz won the battle in the Lahnberg with help from troops from Amöneburg. In 1327, Mainz adopted Giessen with the help of troops from the Electorate of Trier, but the citizens of the town quickly enabled Otto to regain control. Only after Otto's victory at Wetzlar and with the mediation of King John of Luxembourg in 1328 was conciliation made possible.

Otto died on 17 January 1328 in Kassel, and was buried in the Ahnaberg monastery.