To marry a daughter of the French king he agreed that their children would be raised in their mother's faith, thereby becoming ancestor of the Roman Catholic branch of his family.

He was the son of Duke Alexander of Württemberg and Princess Antoinette of Saxe-Coburg-Saalfeld.

Victoria wrote in her journal, "Alexander is very handsome and Ernest has a very kind expression.

"[1] On 17 October 1837 he married Princess Marie of Orléans (1813–1839), daughter of Louis Philippe I, King of the French.

The House of Württemberg's two morganatic branches - the Dukes of Teck (extinct in the male line in 1981) and the Dukes of Urach - were senior by primogeniture to the ducal branch, but were ineligible to inherit the throne.