Parents: Henry II, duke of Brabant, and Sophie of Thuringia
Date of Birth: 24 June 1244
Spouse(s): (1) Adelheid, daughter of Otto I, duke of Brunswick-Lüneburg, then (2) Mechthild, daughter of Dietrich VI, count of Cleves
Predecessor: Henry Raspe (as landgrave of Thuringia)
Reign: 1247 – 1308
Brief: Born to Sophie of Thuringia, Henry was in a unique position to inherit all of his grandfather's vast lands in Germany. But a rival, Henry of Meissen, also had a claim to the territory. After many years of intermittent fighting and feuding, it was agreed that Henry would receive Hesse, and Henry of Meissen the remainder of Thuringia and the title. But Henry had been ruling his portion since 1247 and his lands were only confirmed in 1264. Another rivalry dominated the remainder of his reign, this time with the archbishop of Mainz, Werner II. Werner sought to control the land as a ecclesiastical fief, but agreed to leave it in Henry's hands. But when Henry I sought to annex a portion of Mainz, the archbishop fought back, calling in King Rudolf I of Germany and giving Henry the boot in 1274. Henry decided to join Rudolf's forces and ingratiate himself with the German king, thereby gaining his lands back in 1276. Fourteen years later, Henry defeated the archbishop at the Battle of Fritzlar, solidifying his control over Hesse for good. King Adolf, in 1292, granted Hesse full independence from Mainz and was given additional lands, expanding his territory. Sons born of multiple mothers forced Hesse to fold into a civil war around the same time. Henry I died in 1308 with the succession issue still unresolved. Two sons eventually divided the landgraviate in 1310, while a third, Louis, became bishop of Münster.
Date of Death: 21 December 1308
Successor: Otto I (in Upper Hesse), John (in Lower Hesse)