Question: Why did Prince Sigismund Of Prussia (1864–1866)'s mother die?
Sentence (from "Prince Sigismund of Prussia (1864–1866)"): Prince Francis Frederick Sigismund of Prussia (15 September 1864 – 18 June 1866) was the fourth child and third son of Crown Prince Frederick William of Prussia (later King of Prussia and German Emperor as Frederick III), and Victoria, Princess Royal, eldest daughter of the British Queen Victoria.
Relevant evidence: Yes