William X, Duke of Aquitaine was a prominent nobleman in the 11th century, known for his significant influence in southwestern France. He was born around 1099 and became Duke in 1126, ruling over a vast and wealthy territory that included the important city of Bordeaux. His reign was marked by efforts to strengthen his duchy and expand its power. William X was also notable for his role in the Crusades, as he participated in the Second Crusade. He was a patron of the Church and supported various religious institutions. His legacy continued through his daughter, Eleanor of Aquitaine, who became one of the most powerful women in medieval Europe.