Edward VI became king at the age of nine upon the death of his father, Henry VIII, and a Regency was created. Although he was intellectually precocious (fluent in Greek and Latin, he kept a full journal of his reign), he was not, however, physically robust.
His short reign was dominated by nobles using the Regency to strengthen their own positions. The King's Council, previously dominated by Henry, succumbed to existing factionalism. On Henry's death, Edward Seymour, Earl of Hertford and soon to be Duke of Somerset, the new King's eldest uncle, became Protector.
Seymour was an able soldier; he led a punitive expedition against the Scots, for their failure to fulfil their promise to betroth Mary, Queen of Scots to Edward, which led to Seymour's victory at the Battle of Pinkie Cleugh in 1547 - although he failed to follow this up with satisfactory peace terms.
During Edward's reign, the Church of England became more explicitly Protestant - Edward himself was fiercely so. The Book of Common Prayer was introduced in 1549, aspects of Roman Catholic practices (including statues and stained glass) were eradicated and the marriage of clergy allowed. The imposition of the Prayer Book (which replaced Latin services with English) led to rebellions in Cornwall and Devon.
Despite his military ability, Seymour was too liberal to deal effectively with Kett's rebellion against land enclosures in Norfolk. Seymour was left isolated in the Council and the Duke of Northumberland subsequently overthrew him in 1551. Seymour was executed in 1552, an event which was only briefly mentioned by Edward in his diary: 'Today, the Duke of Somerset had his head cut off on Tower Hill.'
Northumberland took greater trouble to charm and influence Edward; his powerful position as Lord President of the Council was based on his personal ascendancy over the King. However, the young king was ailing. Northumberland hurriedly married his son Lord Guilford Dudley to Lady Jane Grey, one of Henry VIII's great-nieces and a claimant to the throne.
Edward accepted Jane as his heir and, on his death from tuberculosis in 1553, Jane assumed the throne.