When Princess Elizabeth was just 13 years old, she fell in love with her third cousin, then 18-year-old Prince Philip of Greece and Denmark (played by Matt Smith in the Netflix series). Though dating a cousin seems strange to many of us in the United States, it was a long-followed tradition in England. Even Charles Darwin married his own first cousin Emma.
After the two wrote letters back and forth for several years, Philip fell for Elizabeth, too. In 1947, when Elizabeth was 21, the couple announced their engagement publicly. But many thought Prince Philip wasn't good enough for the princess. He lacked wealth, he was born in Greece, not England, and his sisters had married German men with ties to Nazis.
On the morning of their wedding, however, Prince Phillip was given new titles — Duke of Edinburgh, Earl of Merioneth and Baron Greenwich of Greenwich in the County of London — to make him seem more regal and worthy of Princess Elizabeth.