The son of Count Louis the Springer ("the jumper") and his wife Adelheid,[1] he was appointed Landgrave of Thuringia by the Emperor Lothair III in 1131.

According to the succession in his line he should have been called Louis III, but he won Thuringia for his family and, in case of territorial expansion, it was customary to start counting from one.

Thanks to his marriage with Hedwig of Gudensberg he obtained the rule over an extensive heritage, after the death of his father-in-law, Count Giso IV, which led to the union of Thuringia and Hesse.

His close relationship to the King Lothair III favoured his rise into the rank of a prince.

After the death of Lothair, in 1137, Louis decided to support the Hohenstaufen in their struggle for power in the Reich against the Welf party.