Algernon Percy, the son of the 9th Earl of Northumberland, was born in 1602. After the death of his father he became the 10th Earl of Northumberland and in March, 1636, Charles I appointed him Governor of the Fleet.
On April 1638 the Earl of Northumberland became Lord High Admiral of England. He became increasingly critical of the king's policies and on the outbreak of the Civil War refused to support the Royalists and was dismissed from office.
Algernon Percy, 10th Earl of Northumberland, died in 1668.