House of Württemberg
The sons of Frederick I established the ducal house of Württemberg-Neuenstadt, a branch line of the House of Württemberg after a "Fürstbrüderlicher Vergleich" – a mutual agreement made between ducal brothers on 7 June 1617. The eldest son, Johann Friedrich, assumed barony over the Duchy of Württemberg while the second youngest son, Frederick Achilles, was bequeathed Neuenstadt Castle and an annual endowment of 10,000 guilder.