Herbert was a guardian of the young
King Edward VI after the death of Henry VIII in 1547. As an executor of Henry's will and the recipient of valuable grants of land, Herbert was a prominent and powerful person during Edward's reign, with both the protector
Edward Seymour, 1st Duke of Somerset and his rival,
John Dudley, 1st Duke of Northumberland, angling for his support. He threw in his lot with Northumberland, and after Somerset's fall obtained some of his lands in Wiltshire. He was made a
Knight of the Garter in 1549, and created Baron Herbert of Cardiff on 10 October 1551, and 1st Earl of Pembroke (of the tenth creation) the following day, by Edward VI. Herbert's eldest son and heir,
Henry, married
Lady Katherine Grey at Durham House on 25 May 1553, the same day as her sister,
Lady Jane Grey, was married to Northumberland's son
Guilford Dudley. The third couple married that day was Northumberland's youngest daughter,
Katherine Dudley, to
Henry Hastings, 3rd Earl of Huntingdon. After the death of Edward VI, Herbert initially supported Northumberland's attempt to place Jane on the throne. When it became clear that
Lady Mary Tudor would take the throne (as Mary I), he cast his daughter-in-law Katherine out of his house and had the marriage annulled. It was at
Baynard's Castle that the Privy Council met to end the claim of Lady Jane Grey to the throne and proclaim Mary as Queen of England in 1553.
Lady Katherine's father and sister Jane were both executed for
high treason in February 1554 by order of Queen Mary I. Herbert managed to distance himself from the Grey family after their fall, and obtained the new Queen's favour by crushing
Wyatt's rebellion. During the
Italian War of 1551–1559, Herbert commanded the English army sent to France in support of Spain. His troops did not arrive in time for the
Battle of St. Quentin (1557), but played a significant role in the capture of the city afterwards. Pembroke was Mary's most effective commander in the war with France. Mary sometimes suspected Pembroke's loyalty, but he was employed as
governor of Calais, as president of Wales and in other ways. He was also to some extent in the confidence of
Philip II of Spain. The earl retained his place at court under
Elizabeth I until 1569, when he was suspected of favouring the projected marriage between
Mary, Queen of Scots, and
the Duke of Norfolk. Herbert is reported to have had a close bond with his pet dog. Aubrey wrote that he "had a little cur-dog which loved him, and the earl loved the dog. When the earl died the dog would not go from his master's dead body, but pined away, and died under the hearse." Herbert's dog can be seen in the portrait on the left. ==Arms==