Launceston Castle played a role in Cornish politics during the middle of the 16th century. In 1548, Sir William Body, a royal commissioner sent by Edward IV to destroy the Catholic shrines at Helston, was killed by two local Cornish men. In retaliation, 28 local men were arrested and executed at the castle. Anger grew, and in 1549 a wider uprising called the Prayer Book Rebellion took place. It was headed by Sir Humphrey Arundell, who marched up through the county and took Launceston Castle that summer, probably without a struggle. The castle was then used to imprison the royalist leader, Sir Richard Grenville, who died during his detention there. John Russell, the Earl of Bedford, subsequently defeated the rebels and retook Launceston, capturing Arundel who was seized in the street fighting.