Matilda of Flanders
About 1050 AD, William the Conqueror married Matilda of Flanders. Because they were both rich Normans, and there weren't that many rich Normans yet at this time, they were distantly related to each other. The Pope had said that people who were related shouldn't get married, even if they were only second cousins or even third or fourth or fifth cousins. William's enemies pointed this out to the Pope, and they got the Pope to say that God was against this marriage.