Protector of England and effective ruler of England on behalf of Edward VI (1547–49). On the death of Henry VIII in 1547 Edward Seymour (brother of Jane Seymour) took the titles of Duke of Somerset and Lord Protector and won an immediate military success against Scotland at the Battle of Pinkie. His attempts to enforce the use of a Protestant English Prayer Book by Act of Uniformity (1549) sparked off the Western Rising. Kett’s Rebellion, coinciding with discontent among magnates grouped around his rival, the Earl of Warwick (later the Duke of Northumberland), led to his downfall. He was overthrown in 1549 and executed on the orders of Northumberland in 1551.