Melisende was the daughter of the king of the Frankish kingdom of Jerusalem and his Armenian wife. Christian crusaders had wrested Jerusalem from the Muslims in 1099.
Melisende began her reign with her father at the end of his life. In 1129 she married Fulk V of Anjou (France). In 1131, they became joint rulers of Jerusalem, although Fulk outshone Melisende and effectively ignored her. In the mid 1130s this changed. Rumors flew, accusing Melisende of having an affair with Fulk's biggest rival, the rebel Hugh II. Fulk chose to believe the rumors and provoked a war against Melisende and her supporters. But her forces prevailed, and her fortunes changed. She insisted on strong peace-terms, which included her admission to the inner councils of the kingdom. She was given great leeway in promoting the arts and in founding a huge abbey. Thereafter, wrote the historian William of Tyre, Fulk "never tried to initiate anything, even in trivial matters, with her foreknowledge."
After Fulk's death Melisende became regent for her 13 year old son, Baldwin.
But by now, however, she had had a taste of real power and she became determined to hold unto it. 1145 was the year Baldwin was to celebrate the attainment of his majority. Melisende ignored the date, easing him out of every place of influence, omitting his name from public acts.
Baldwin put up with this mother's actions until 1152. Complaining to the high court of the kingdom that his mother would not let him rule, he demanded that the realm be divided between mother and son. This is what happened. Melisende ruled Judaea and Samaria and Baldwin the north.
The division didn't last for long. While Melisende's supporters urged the Franks to take account of her efficient administration and ability to rule, it was Baldwin who held the right to rule. This alone was enough to gain greater support for his cause. After a brief military campaign against her, he overwhelmed his mother's army. Her last stronghold was the cramped confines of the Tower of David in Jerusalem.
In spite of their past disagreements, mother and son were reconciled, and she remained one of his closest advisers until her death.
But these rivalries greatly damaged the future of the crusader's Kingdom of Jerusalem. The Muslims took great tracts of territories from the crusaders during the period of Melisende's troubled reign. As a result, Jerusalem never again let a woman rule. When in 1186 a woman actually inherited the crown, her husband was effectively elevated to rule in her place.Of course, the rivalries between Melisende and her husband and son were not the only reasons Christians had trouble holding on the Jerusalem.