Her name is undoubtedly less familiar than that of her grandmother, Eleanor of Aquitaine, or that of her famous conqueror son, Fernando III, yet during her lifetime, Berenguela of Castile (1180-1246) was one of the most powerful women in Europe. As queen-consort of Alfonso IX of Leon, she acquired the troubled boundary lands between the kingdoms of Castile and Leon and forged alliances with powerful nobles on both sides. Even after her marriage was dissolved, she continued to strengthen these connections as a member of her father's court. On her brother's death, she inherited the Castilian...