Christian August II, Duke of Schleswig-Holstein-Sonderburg-Augustenburg (19 July 1798 – 11 March 1869, Christian Carl Frederik August), commonly known as Christian, Duke of Augustenborg, was a Danish/German prince and statesman. During the 1850s and 1860s, he was a claimant to first duke of the whole provinces of Schleswig and Holstein, and a candidate to become king of Denmark following the death of King Frederick VII. He was the father-in-law of Princess Helena (daughter of Queen Victoria) and the paternal grandfather of Augusta Victoria, Empress of Germany and wife of Kaiser Wilhelm II. Family and lineage He was closely related to Kings Christian VII, Frederick VI and Christian VIII of Denmark through his mother and was a claimant for the Danish throne in the 1860s. Born a prince of the House of Schleswig-Holstein-Sonderburg-Augustenburg and scion of a cadet-line descendant of the Danish royal House of Oldenburg, Christian August was the fiefholder of Augustenborg and Sønderborg. He was also a claimant to the rulership of the provinces of Slesvig and Holstein, and he was also a candidate to become king of Denmark during the succession crisis caused by the childlessness of King Frederick VII of Denmark. He lost the chance to ascend the throne to his distant kinsman, Prince Christian of Schleswig-Holstein-Sonderburg-Beck. Christian August was the eldest son and heir of Frederik Christian II, Duke of Augustenborg and his wife Princess Louise Auguste of Denmark. His father was the head of the senior cadet branch of the ruling house of Denmark, and thus the nearest agnatic kin of the kings of Denmark. Furthermore, his mother Louisa Auguste was (officially) the daughter of King Christian VII of Denmark, the sister of King Frederick VI and the first cousin of King Christian VIII. Due to all this, Christian August was high in the line of succession to the Danish throne. He also enjoyed additional influence in the Danish court because his sister, Caroline Amalie, was the beloved second wife of King Christian VIII (his mother's cousin). Christian August's family lost out in the competition for the throne of Denmark mainly because of the widely accepted belief that his mother was actually fathered by Johann Friedrich Struensee, Christian VII's royal physician. If true, this would mean Christian August was not a true legitimate descendant of Frederick III, the first hereditary monarch of Denmark. His claim was further weakened by having married for love to Countess