The eldest son of William Ayscue, a courtier to King Charles I, George Ayscue was the godson of George Abbot, Archbishop of Canterbury. He was knighted by King Charles in 1641 under the controversial distraint of knighthood policy and married Mary Fotherby, daughter of the bishop of Salisbury, around 1645. Nothing is known of Ayscue's naval career until the summer of 1646, when he was serving in Parliament's navy as captain of the Expedition at the siege of Pendennis Castle in Cornwall. He was appointed governor of the Isles of Scilly until January 1647, then returned to sea as captain of the Antelope (1647) and the Lion (1648).
When William Batten defected to the Royalists in 1648, Ayscue's influence kept most of the fleet loyal to Parliament. He was appointed Vice-Admiral to the Earl of Warwick in the fleet that confronted the Prince of Wales and blockaded the Royalists in Helvoetsluys in August 1648. Ayscue was then promoted to Admiral of the Irish Sea fleet with responsibility for keeping the sea route open to Dublin when it was besieged by the Marquis of Ormond. His fleet supported Cromwell's invasion of Ireland in 1649 and conveyed the heavy guns by sea to the siege of Drogheda.
In 1650, Ayscue was appointed commander of the squadron sent to capture Barbados from the Royalists. Before setting out, he was diverted to serve as second-in-command to Robert Blake in his attack on the Scilly Isles, which were held for Charles II by Sir John Grenville. After the recapture of Scilly, Ayscue sailed for Barbados in August 1651. He arrived in October and blockaded the island. The Royalist governor Lord Willoughby surrendered to Ayscue in January 1652 and Barbados submitted to the Commonwealth. Other colonies in the West Indies and America submitted without further resistance.
Ayscue arrived back in England in May 1652. During the First Anglo-Dutch War, he was active in harassing Dutch convoys in the Channel. In July, Ayscue's squadron prepared to engage a much larger Dutch fleet commanded by Tromp, but the Dutch sailed away when the wind changed. In August 1652, Ayscue's squadron was reinforced. With the George as his flagship, he patrolled the Channel with 38 men-of-war and armed merchantmen. On 16 August, he clashed with Admiral de Ruyter at the battle of Plymouth. Ayscue retired from his command soon after the battle. The reasons for his retirement are unclear. He claimed ill-health, but he was also known to dislike going to war against a Protestant nation. Ayscue remained in retirement at Chertsey in Surrey for several years. In 1658, Cromwell persuaded him to go as a naval adviser to Charles X of Sweden, where he remained until the Restoration.
Ayscue was appointed an Admiral in Charles II's navy and fought in the Second Anglo-Dutch War. During the Four Days' Battle (June 1666), Ayscue's ship ran aground. He was taken prisoner by the Dutch and held captive until the war ended in 1667. He was appointed to another command when the Third Anglo-Dutch War broke out, but died in April 1672 before he could take it up.
References:
J. D. Davies, Sir George Ayscue, Oxford DNB, 2004
Bernard Capp, Cromwell's Navy, the Fleet and the English Revolution, 1989