He was the eldest son of Frederick William, Elector of Hesse (1802–1875), and his morganatic wife, Gertrude Falkenstein (1803–1882), whom he later elevated to Princess of Hanau and Hořowitz (German: Fürstin von Hanau und zu Hořowitz).

[1] Although his father was Elector of Hesse until the electorate was abolished in 1866 (after which he was exiled to Austria),[2] upon his father's death in 1875, Friedrich Wilhelm and his younger brothers were all excluded from the line of succession due to his parent's morganatic marriage.

They daughter of actors Carl Birnbaum and Maria Sargany, she became pregnant and her father threatened to kill Auguste and himself if they didn't marry.

She died of tuberculosis in 1862 in Bad Cannstatt, where they had taken refuge under the protection of King Charles of Württemberg.

Although married in 1875, he already had two sons with her:[3] Prince Friedrich died at Hořovice in Beroun District in the Central Bohemian Region (today a part of the Czech Republic) on 24 March 1889.