John Dudley, 1st Duke of Northumberland was an English general, admiral, and politician, who led the government of the young King Edward VI from 1550 until 1553, and unsuccessfully tried to install Lady Jane Grey on the English throne after the King's death. The son of Edmund Dudley, a minister of Henry VII executed by Henry VIII, John Dudley became the ward of Sir Edward Guildford at the age of seven. Dudley grew up in Guildford's household together with his future wife, Guildford's daughter Jane, with whom he was to have 13 children. Dudley served as Vice-Admiral and Lord Admiral from 1537 until 1547, during which time he set novel standards of navy organisation and was an innovative commander at sea. He also developed a strong interest in overseas exploration. Dudley took part in the 1544 campaigns in Scotland and France and was one of Henry VIII's intimates in the last years of the reign. He was also a leader of the religious reform party at court.

Edward VI was King of England and Ireland from 28 January 1547 until his death in 1553. He was crowned on 20 February 1547 at the age of nine. The only surviving son of Henry VIII by his third wife, Jane Seymour, Edward was the first English monarch to be raised as a Protestant. During his reign, the realm was governed by a regency council because Edward never reached maturity. The council was first led by his uncle Edward Seymour, 1st Duke of Somerset (1547–1549), and then by John Dudley, 1st Duke of Northumberland (1550–1553).