We all know that Archduke Franz Ferdinand was assassinated in 1914 in Sarajevo which in part led to the First World War. You may also know that Franz Joseph's son and heir Prince Rudolf committed suicide with his lover in 1889, also that Karl Ludwig (Franz Joseph's brother and Franz Ferdinand's father) died of typhoid fever in 1896, and finally that in 1906 Franz Ferdinand's brother Otto died of syphilis. So relating to my question. With Franz Joseph's son, brother, and two nephews dead upon his death in 1916, why did the throne pass to his younger nephew's son, Otto's son Charles, and not Franz Ferdinand's eldest son Maximilian?
Were succession laws different in the Austro-Hungarian Empire than they were in the United Kingdom (with which I am the most familiar)? Did age play a role in their decision to crown Charles as he was much older than Maximilian who was just a child?
A number of royal houses had house laws, inter alia prohibiting members from making "unequal marriages". Habsburg custom prohibited marrying any but royal blood, and in particular, the Familienstatut (1839) said that the head of the house had to approve of all marriages of princes and princesses, and without it, while the marriage was valid in canon law, the marriage would have no claim to name, arms, succession, property, et cetera. But the head of the family could approve a morganatic marriage. A morganatic marriage is one where the spouse and children got no marriage titles or succession. (From matrimonium ad morganaticam, the gift (dowry) given by the groom to the bride on the morning of the marriage, as in "that's all yer gettin', toots".) After some time, Franz Joseph finally relented and allowed Franz Ferdinand to marry this mere lady in waiting Countess Sophie Chotek ... but morganatically. She was usually not seen at formal public events near him. Franz Joseph eventually gave her the title Duchess of Hohenberg, but archduchesses and mediatized ladies took precedence of her. At her and FF's hurried and badly attended funeral, her coffin was lower than her husband's, and it bore only the gloves of a lady in waiting. They were buried together ... at the Habsburg summer home, because the family crypt was barred to her and Franz Ferdinand wanted to be buried with her.