One little word can hold such big meaning.

The royal family is no stranger to tradition. In weddings and in everyday life, they follow a famously rigid protocol. But Princess Diana made a splash by breaking those rules—starting on her first day in the family. She even launched a new wedding-day tradition in the process.

Few celebrations are more steeped in tradition than weddings, especially for the royal family. Since 1662, the Anglican Book of Common Prayer listed this line in its marriage vows: “to love, cherish, and to obey, till death us do part.”

The People’s Princess was fine with all but one little word: obey. Most English brides at the time left that word out because it suggested the husband was dominant, but no royal woman had ever messed with the traditional wedding vows before. After great debate, Princess Diana and Prince Charles agreed to leave it out. Don’t miss these other 12 times the royal family broke their own protocol.

Diana’s powerful statement about husband-wife power dynamics was a controversy in 1981, but little did she know the ripple effect it would create. Kate Middleton left “obey” out when she married Prince William 30 years later, and so did Meghan Markle when she wed Prince Harry. At the most recent royal wedding, women are still following Diana’s footsteps. Even though her mom, Sarah Ferguson, Duchess of York, stuck to tradition when marrying into the royal family in 1986, Princess Eugenie promised to love and cherish her new husband … but not to obey him. Next, learn the secrets about Princess Diana no one knew until after her death.