In 1657 he commanded the English force which cooperated with the French in Flanders in the Anglo-Spanish War and was lost at sea when returning to England.
[3] On the formation of the New Model Army he obtained command of a troop in Vermuyden's (afterwards Cromwell's) regiment of horse, and distinguished himself at the storming of Bridgewater.
[5] Reynolds was popular with soldiers of advanced political views, and in 1648 was put in command of a regiment of horse consisting mainly of volunteer troops raised on the occasion of the Second Civil War,[6] He was one of the officers in charge of King Charles I at Hurst Castle in December 1648.
[10] Reynolds and his regiment landed at Dublin on 25 July 1649, and played an important part in the victory which Colonel Michael Jones gained over the Marquis of Ormonde at the Battle of Rathmines on 2 August.
[12] About April 1651 Reynolds was made commissary-general of the horse in Ireland, and in that capacity assisted in the sieges of Limerick and Galway, and signed capitulations with Colonel Fitzpatrick, Lord Clanricarde, and other Irish leaders.
[27] He landed in France in May, and was received with studied courtesy by Cardinal Mazarin,[28] but he found it difficult to persuade Marshal Turenne to attack the coast towns of Flanders, and complained that English interests were throughout postponed to French.
[30] Mardyck was taken on 23 September, and Reynolds installed there as governor of the English garrison; but the task of keeping so weakly fortified a post was one of great difficulty.
Though Reynolds repulsed one attack with considerable loss to the assailants (22 October), both the English troops serving with Turenne and the garrison of Mardyke were so reduced by disease that at the beginning of December only eighteen hundred out of the six thousand were fit for service.
[34] Rumours that he had for some reason lost Cromwell's favour had certainly reached Reynolds, as a letter from Sir Francis Russell to his son-in-law proves.
[36] By his will, which was disputed, Reynolds left the manor of Carrick to his brother Robert, and his other lands in England and Ireland to James Calthorpe, the husband of his sister Dorothy.