Magna Charta. Signed during King John's reign because of baronial opposition to his endless taxes trying to recover his fathers holdings in France (he never did). This is considered by many to be the beginning of English common law, upon which the American Judicial System was based (and still referred to in court).
Eleanor of Aquitaine .... At age 15 she married Louis VII, King of France, bringing into the union her vast possessions from the River Loire to the Pyrenees. Only a few years later, at age 19, she knelt in the cathedral of Vézelay before the celebrated Abbé Bernard of Clairvaux offering him thousands of her vassals for the Second Crusade. It was said that Queen Eleanor appeared at Vézelay dressed like an Amazon galloping through the crowds on a white horse, urging them to join the crusades.