"Frederick Achilles of Württemberg-Neuenstadt (5 May 1591 – 30 December 1631) was the first Duke of Württemberg-Neuenstadt from 1617 until 1631.
The Duchy of Württemberg-Neuenstadt was a branch line of the ducal House of Württemberg in the 17th and 18th century named after the town of residence, Neuenstadt.
Duke Frederick Achilles (German: Friedrich Achilles) was the second youngest son of Duke Frederick I. Following a Fürstbrüderlicher Vergleich - a mutual agreement made between ducal brothers on 7 June 1617 (Julian calendar: 28 May), the sons of Frederick I split the inheritance such that the eldest son, Johann Frederick, assumed rule of the Duchy of Württemberg while his remaining brothers assumed possession of other ducal properties." - (en.wikipedia.org 03.11.2019)