Henry I of England was the fourth son of William the Conqueror and became king in 1100 after the death of his brother, William II. He is known for his efforts to strengthen the monarchy and improve the administration of justice. Henry introduced the use of the Exchequer to manage finances and implemented legal reforms that laid the groundwork for future English law. During his reign, Henry I faced challenges, including conflicts with his barons and issues of succession. He married Matilda of Scotland and had several children, but his only legitimate son, William Adelin, died young. Henry's death in 1135 led to a succession crisis, sparking a civil war known as the Anarchy.