This Day In History: July 10, 1553 On July 10, 1553, Lady Jane Grey, the great-niece of King Henry VIII, ascended the throne of England as the result of a plot masterminded by John Dudley, Earl of Northumberland. Her “reign,” if you could call it that, lasted all of nine days until Mary Tudor and her supporters marched into London, … Continue reading This Day in History: July 10th