King George III. The couple were second cousins to each other, being great-grandchildren of George I of Great Britain. As such, they were not related in a particularly close degree, yet there had been many bonds of marriage between the House of Brunswick-Bevern and the House of Hanover, themselves both branches of the House of Welf. Some commentators have pointed to inbreeding as a possible cause for the fact that many of the couple's children had physical, mental or psychological disabilities. Indeed, the duke was once moved to describe his children to von Massenbach as "mostly cripples in mind and body." Shortly after they married, the prince had the Schloss Richmond built for his wife. It was in English architectural style and with an English landscape garden, to remind her of her home. The duke and his wife Augusta had four sons and three daughters. Three of their four sons had major debilities. Their eldest son, Karl Georg August (1766–1806) was named heir apparent, but had a significant learning disability and was regarded as "well-nigh imbecile." Nevertheless, he was married in 1790 to Frederika of Orange-Nassau, daughter of William V, Prince of Orange, a gentle, good-hearted woman who remained devoted to him to the end. He died childless at the age of 40 in 1806, shortly before his father. The second son, Georg Wilhelm Christian (1769–1811), had an even more severe learning disability than his elder brother. He was declared incapacitated and excluded from the succession. He never married. The couple's third son was August (1770–1822). He was blind and also excluded from the succession. He, too, never married. The fourth son, Friedrich Wilhelm (1771 – 16 June 1815), was sound of mind and body. He eventually succeeded his father, married and sired two sons. Frederick and Augusta also had three daughters, two of whom reached adulthood. Neither of them was disabled, but both of them had similar, disastrous trajectories in life. Both of them were married to future kings, both made extreme failures of their marriages, both had extremely acrimonious relations with their husbands, and both were accused by them of similar faults: adultery, uncouth behavior, absence of dignity, falsehood and utter fecklessness. The elder daughter, Auguste Caroline Friederike (1764–1788), was the wife of the future king Frederick I of Württemberg and mother of the future William I of Württemberg. She separated from her husband and died in Russia