The Magna Carta, Millennia, and Marriage

Came across this in an article on the thorny history of the Magna Carta, noting the marital lowlights of its author, King John. I was reading this the same week SCOTUS justices fretted they would be tinkering with "millennia" of marital history. In 1189, John married his cousin Isabella of Gloucester. (When she had no children, he had their marriage ended, locked her in his castle, and then sold