a certain Captain Robert Stewart came over to Germany as lieutenant-colonel in a regiment of Scots volunteers commanded by Colonel James Lumsden [q. v.], ‘having served at first as ensign and lieutenant to Captain Mackenzie under this regiment, and then after came again unto Spruce, captain under Sir John Hamilton's regiment, in May 1629. And was preferred after the intaking of Virtzberg, having been before at the battle of Leipsigh’ (cf. also Grant, Memoirs of Sir John Hepburn, p. 154). On 26 April 1636 Chancellor Oxenstjerna applied to Charles I for permission for Stewart to enlist troops in England for service in Germany (Clarendon State Papers, i. 516), and on 15 May 1637 Charles granted him a warrant to take up in Ireland and transport four hundred volunteers for the service of the crown of Sweden (Lodge, Peerage).
On 11 April 1638 Stewart was appointed governor of Culmore Castle on Lough Foyle, commanding the approach by sea to Londonderry, of which city he was on 25 Feb. returned a member to the Irish parliament which met in 1639. After the outbreak of the rebellion of 1641 he received a commission, dated 16 Nov., from Charles I to raise and command a thousand foot and a troop of horse for his majesty's service. But before the commission arrived he and Sir William Stewart had got together a thousand men, with which they managed to relieve Captain Audley Mervyn at Augher, and, though they were unable to prevent Strabane falling into the hands of Sir Phelim O'Neill [q. v.], their efforts were entirely successful in securing the barony of Raphoe, ‘in which the safety of the city of Londonderry was highly concerned’ (Mervyn, Relation). Not, however, receiving any support either from England or the government at Dublin, Stewart was forced to exhaust his own resources, and in the following spring his men were reduced to great extremities. Nevertheless he and Sir William Stewart on 16 June inflicted a severe defeat, ‘after the sharpest action that had been fought in the north,’ on Sir Phelim O'Neill at Glenmaquin, near Raphoe, though want of provisions disabled them from profiting by their victory. The merit of the action seems to have rested mainly with Stewart.
Early in the following year, 1643, Stewart was, on the death of Sir John Vaughan, appointed governor of Londonderry, in addition to his charge at Culmore. He was superseded next year by Colonel Audley Mervyn; but in the meanwhile the appointment did not prevent him acting, so far as circumstances allowed, on the offensive. In May he made an excursion as far as the borders of co. Monaghan, capturing a number of prisoners, and burning the enemy's quarters. Returning in June, he surprised Owen Roe O'Neill [q. v.], at the head of about sixteen hundred men, in the neighbourhood of Clones. His force greatly outnumbered that of O'Neill, but the conflict was a desperate one. The Irish were defeated with serious loss, ‘most of their arms being taken, and the greatest part of the foreign officers which came with Owen O'Neill killed or taken prisoners.’ Want of provisions and ammunition, however, again prevented Stewart improving his victory, and, after capturing the castle of Denge and ravaging the country round about Dungannon, Charlemont, and Kinard, he returned to his headquarters. His position, always one of great difficulty, became extremely uncomfortable after the arrival of orders for the Scots Army under Robert Monro (d. 1680?) [q. v.]—called the New Scots, in order to distinguish them from the army of the Scottish planters—to take the covenant and the proclamation of the lords justices of 18 Dec. condemning it. Unwilling at first to cut themselves off from all assistance from Scotland, Stewart and the other royalist commanders refrained from publishing the proclamation; but, after meeting at Belfast on 2 Jan. 1644 to consider the situation, they agreed not to accept the covenant. Matters after this remained in an uncertain state till the beginning of April, when a number of kirk ministers arrived with instructions to enforce the taking of the covenant. Stewart continued obdurately opposed to it, and, though most of his officers were seduced by Sir Frederick Hamilton, he bravely read the lords justices' proclamation against it at the head of his regiment. But after the appointment of Monro with a commission from the parliament of England on 27 April to the chief command of all the English as well as Scottish forces in Ulster, he gave way, and at a meeting of ministers at Coleraine publicly took the covenant, saying, ‘Now I will be as arrant a covenanter as any of you’ (Adair, True Narrative, pp. 113–17).
After this step his difficulties perceptibly diminished. On 7 Feb. 1645 the committee of both kingdoms ordered provisions to be at once despatched to Lough Swilly for him and Sir William Stewart, and on 8 Oct., in consequence of his capture of Sligo Castle, of which he was in June appointed governor, passed him a vote of thanks for his good services. As a result of Monro's precipitancy in fighting Owen O'Neill, Stewart arrived too late on the scene of action to take part in the battle of Benburb on 5 June 1646. He had reached Augher when he
