The second son of Isaac Astley of Melton Constable, Norfolk, he served in the Dutch army's English contingent during the Dutch war for independence (1598-1609); won distinction for his courage and ability, particularly at the battle of Nieuwpoort (July 2, 1600) and in the long siege of Ostend (July 11, 1601-September 20, 1604); he returned to England after the implementation of the Twelve Years' Truce (1609), but was in Germany at the beginning of the Thirty Years' War; he fought under Elector
Frederick V's general, Christian of Anhalt-Bernburg (1619-1622), and later under Gustavus Adolphus (1630-1632); returned to England a distinguished soldier and was appointed governor of Plymouth and the Isle of St.