Eleanor of Aquitaine

The view of women in Medieval society has been largely shaped by seeing it through a modern lens.  As a result, I think we tend to ignore certain subtleties in that society.  In particular, the popular view of women at this time is that they were powerless and downtrodden--which is true by today's standards, but I don't think it's entirely accurate.

First, only a small number of people in the Middle Ages had any real power, which here I will define as options (choices) and influence over others.  This was the case whether they were male or female.  Only farther up the wealth and societal ladder does the question of power really begin to have much of a context.  Women were used as bargaining chips in securing advantageous alliances or in acquiring lands (from which wealth and power derived.)  She benefited from such a marriage as well, providing her with a standard of living that was equal to or greater than she had been raised with, and which was above that of many women.  As long as she was able to provide her husband with an heir, her place was generally secure.

These times were a time for warfare, and while her husband was away, the woman had control over her husband's holdings.  She assumed his authority in his absence, and had control over the purse, as well.  Once out of her father's household, many women acquired significant power, albeit behind the scenes through influence over her husband or the men around him.

Consider Eleanor of Aquitaine.  Born in 1122, she inherited the duchy of Aquitaine (in France) directly from her father, and was thus ruler of Aquitaine in her own right.  A month after her marriage to Louis of France, he became King of France, and she actually accompanied him on the Second Crusade.  Her marriage to Louis VII failed, very likely because she failed to provide him an heir, and despite the efforts of the Pope, Louis was determined to divorce her.

In 1152 she married Henry Fitz-Empress, the Duke of Normandy through his mother (a daughter of King Henry I of England) and the Count of Anjou through his father.  After the deaths of both Henry I and his successor, Stephen, Henry Fitz-Empress became Henry II, King of England, and Eleanor became queen.  Two of her sons became King of England after Henry II's death, and Eleanor also continued to take an active role in ruling Aquitaine.

While her son, King Richard I, was on crusade, his brother John allied with France and tried to take the throne.  It was Eleanor who helped to maintain the support of those in England for Richard, defeating John.  After Richard's death, Eleanor's grandson, Arthur of Brittany, tried to seize the throne, and it was Eleanor, aged 80, who held out against his forces until John could muster a force to defeat him. 

It was Eleanor's strength, in part, that held England together during Richard's reign.  He spent very little time in England and had little interest in administering the affairs of the country.  And it was Eleanor's power and influence that helped enable John to defeat Arthur of Brittany and assume the throne after Richard's death.