Perhaps no example better represents the practice of inter-marriage better than that of the Spanish Habsburgs. Over the course of 200 years, a total of 11 marriages were conducted by the Hapsburg kings, with nine of them occurring between the degree of third cousin or closer. The process of maintaining diplomatic ties through marriage was so common that the Habsburgs had a famous motto attributed to their tactics, “Let others wage war. You, happy Austria, marry!”

More recently, Queen Victoria of England was assigned the moniker of the ‘Grandmother of Europe’ due to her frequent matchmaking. Victoria had nine children and 42 grandchildren, who, after her death in 1901, continued to rule over large parts of Europe. Even today, out of the 28 remaining monarchies, five are held by descendants of Victoria. The current Queen of England herself is related to Victoria, as is her late husband, Prince Phillip.

The photograph above speaks volumes on the impact Victoria had around Europe. Taken in 1910, at the state funeral of Victoria’s son, it is the only photograph featuring nine simultaneously reigning monarchs. There were supposed to be 10 monarchs, but the Tsar of Russia was unable to attend. All ten sovereigns were related to Victoria. In fact, during the outbreak of World War One, the three greatest powers in Europe, Germany, Russia, and England, were all ruled by grandchildren of Victoria with the German Kaiser once remarking that, if his grandmother were alive at the time, she never would have allowed the War to happen