No reference to his movements at the beginning of the war has survived. We do not know (though from his residence in Nottingham it is probable) whether he was among the angry gentlemen who threatened to throw Lord Newark, the Lord Lieutenant, and Sir John Digby, the Sheriff, from the window when, early in August, 1642, they attempted to lay hands on the county magazine for the king's service ; nor again if he was among the spectators who witnessed Charles's banner fling its defiance from Standard Hill on the 22nd of that month. It seems highly probable that he was one of those who supported John Hutchinson when, after the Battle of Edgehill, he seized Nottingham Castle in order to prevent Digby from securing it for the king, and that he and his Horse must have served in that first siege of Newark in February, 1643, which was ruined by the treachery of the parliamentary commander, Colonel Ballard—but again confirmatory evidence is lacking. It is reasonably certain that he was present in the composite force which collected at Nottingham in May, 1643, under Lord Grey of Groby to oppose the threatened advance south from Yorkshire of the king's general in the north, the Earl of Newcastle, and that he now saw for the first time the uncouth but forceful figure of Colonel Oliver Cromwell, who had fought his way up from the eastern counties to join Grey, winning outside Grantham a cavalry skirmish which was prophetic of much that lay in the future. On two victorious fields the high-spirited young beau sabreur was destined to fight under that dark genius before death claimed him. The first was not long delayed. In the middle of July Lord Willoughby of Parham attacked and captured the town of Gainsborough which had been held for the king by the Earl of Kingston, the lord of Holme Pierrepont; but Willoughby was at once besieged in turn by a royalist force from Newark and by the advance guard of the Earl of Newcastle who was moving south into Lincolnshire. Sir John Meldrum, the parliamentary commander in Nottinghamshire, and Cromwell, who had in the meantime returned to the eastern counties, were both ordered to march to Willoughby's aid. Their junction was effected at Grantham on July 26th, Meldrum having with him about 300 of the Nottinghamshire horse, including Colonel Thornhagh and his major, Henry Ireton. Pushing north they encountered the royalists under Charles Cavendish on the 28th just to the north of Lea on the Gainsborough road. Gaining the sandy plateau where Cavendish was posted, they charged at once, the Nottinghamshire troops forming the main battle, and as the puritan sword did its work the cavaliers broke and streamed back in headlong flight. Colonel Thornhagh "who had fought very gallantly" was actually taken prisoner, stripped and wounded while he was unarmed; but the locality was well-known ground to him for his own estates lay in the neighbourhood, and he managed to creep into one of his tenants houses and from there to get to Lincoln.1 Potentially, as Gardiner wrote, Gainsborough was the turning point of the war2 for it first revealed on a large stage the capacity of the parliamentarian cavalry and the brilliance of the Huntingdon colonel, and it is perhaps not altogether fanciful to conjecture that as the deep purposeful eyes of Cromwell watched Thornhagh and his men thrust themselves through the royalists' ranks an impression was registered that here was a man with the root of the matter in him—a fit instrument for that grim divine plan which Oliver served.

When he had recovered from his wounds Colonel Thornhagh returned to Nottingham. He was with Hutchinson in the castle in September when Sir Richard Byron, the royalist governor of Newark, seized the town and held it for five days (September 18th-23rd) and also in December when Newcastle invaded the county, established himself at Welbeck, and quartered his troops almost up to the confines of Nottingham.3 The threatened siege was averted by the timely alliance between parliament and the Scots which brought a Scottish army across the border on January 19th, and forced Newcastle to race back in order to defend Yorkshire; but on the 16th the Newarkers broke into the town again and occupied St. Peter's Church and the neighbouring lanes and buildings. Colonel Thornhagh, dismounting his troopers, joined the foot and led out a sally which drove the enemy from the town. Eighty prisoners were taken, and the cavaliers left behind a litter of dead and wounded lying in the snow.4

Newcastle's retreat threw the royalists in Nottinghamshire on to the defensive, and by the middle of February the roundheads had collected a new army of from 5,000 to 7,000 men from Lincolnshire, Nottinghamshire and Derbyshire under Sir John Meldrum in order to besiege Newark. Thornhagh, who had been nominated by parliament as High Sheriff of his county in the preceding December5 was present in command of the Nottinghamshire horse. By March the town was so straitened that Meldrum hoped to take it in six days, and the garrison sent urgent appeals for help to the king who was then at Oxford. To save the town, which was an essential bastion of the royalist cause in the north, Charles ordered Prince Rupert to hasten to its relief. From Chester, where he then was, the Prince set out on March 12th, and, collecting detachments from various royalist garrisons as he advanced, he reached Bingham on the 20th with from 6,000 to 7,000 men.6 According to Clarendons Meldrum was taken entirely unawares by his approach, but if this was so his intelligence service must have been deplorable, for Rupert's intentions were well known to nearly all the pamphleteers of the time.7 His dispositions when he heard of the royalists' approach certainly seem to point to surprise or incapacity, for, neglecting the advice of some of his subordinate commanders to fall back on Lincoln, he crowded his foot into a strongly fortified work to the north of Newark, called the Spittal, where, it would appear to the amateur strategist, he was in obvious danger of being trapped between the garrison and the relieving force unless he could count upon prompt succour from the Earl of Manchester's forces in the Eastern Association counties.8 Meanwhile Rupert, fearing that his adversary was about to retreat, pushed forward his horse through the moonlit early hours of the 21st. Sweeping round the besieged town to the south, his squadrons drew out beyond Balderton and Coddington and reached the crest of Beacon Hill about nine o'clock in the morning. Looking down towards Newark they could see Meldrum's foot in the Spittal, and the bridge of boats which led from it over to the island beyond, while in the valley between the parliamentarian horse, 1,500 strong, was drawn up under Thornhagh and Major Rossiter of Lincolnshire to meet the coming attack. Which side charged first is uncertain, but in a few minutes the two battle lines were merged into one shapeless tangle, and the valley echoed with drumming hoofs and the demonic symphony of clashing mail, exultant war cries and death's staccato shrieks as man and beast dropped beneath the pistol shots and swinging sabres. It was the largest conflict fought on Nottinghamshire soil during the war,9 and it was fiercely contested before the roundheads broke and fell back on the Spittal. The next morning Meldrum capitulated and Newark was relieved. Thornhagh and Rossiter both did brilliant service in this action, and though they failed to withstand the Prince they proved to the world that they were foemen worthy to cross swords with that tornado on horseback. Mrs. Hutchinson states that Colonel Thornhagh charged Rupert's own squadrons and broke his way through the whole royalist army;10 but he was shot in the arm and body so seriously that his wounds were expected to be fatal. Fortunately it proved possible to send him in a wagon to Nottingham,11 and there he recuperated.

In August, when the Earl of Manchester marched south after the Battle of Marston Moor and obliged Welbeck12 (where there was a royalist garrison) to capitulate, he was made governor of the parliamentarian troops who were put in to hold the place.13 But it was the close of the year before he appeared again on active service. At the end of November he led out a raiding party and fell suddenly upon Sir John Girlington's regiment of horse which was stationed at Muskham Bridge near Newark, capturing some officers, horses and colours.14 The following month (December) he marched against Thurgarton, which was held for the king by its owner Sir Roger Cooper, and after storming the neighbouring church and stables forced the garrison of fifty to surrender and sent them as prisoners to Nottingham.15

During the first half of 1645 he seems to have been engaged in the efforts which were being made by the parliamentary authorities to straiten Newark and limit in some measure the raiding area of its enterprising garrison. Letters were sent to the two Fairfaxes asking them to provide troops for this purpose, and Thornhagh himself was urged to do all he could to keep the enemy in.16 In February he hastily attempted to storm the house of Gervase Lee at Norwell, into which the New-arkers had put a garrison, but he was repulsed, and the arrival of Sir Marmaduke Langdale, who had been sent north by the king to bring relief to Pontefract, obliged him to relinquish his attack.17 He does not seem to have fought at Naseby (June 14th) nor to have been present when a royalist force from Newark succeeded in surprising and recapturing Welbeck on July 16th; but the next month he was once more caught in the main stream of the war. The king, in the hope of effecting a junction with the Earl of Montrose in Scotland, had pushed north and reached Doncaster on August 19th. General Poyntz, who commanded all the roundhead forces in the north, massed troops to bar his progress, and the presence of Scottish cavalry at Rotherham at length obliged Charles to retire. He left Newark on August 22nd and moved south followed by Poyntz, Rossiter and Thornhagh. The last-named was sent by Poyntz to report to the Houses at Westminster and on August 30th he was thanked personally by the Speaker for his "many great and faithful services" and voted two "very good serviceable horses" as a mark of parliament's esteem.18 As the king fell back through Oxford to Hereford and Raglan Poyntz followed, and when in September Charles went north to relieve the royalist garrison of Chester he was still hot on his trail. On the 24th the two forces met in a fierce cavalry battle on Rowton Heath, two miles from Chester. The rout of the royalists was largely due to the good service of the Nottinghamshire Horse and their colonel, and after the battle they were voted £1,000 by parliament for their gallantry.19 "The enemy came down to us, and in a career charged," wrote Thornhagh, "We stood and moved not till they had fired, which made Gerrard20 swear (God damn him) 'the rogues will not stir.' Upon those words we clapped spurs to our horses, and gave him such a charge as I dare say was the accomplishment of the victory, for we routed him and pursued him and made him fly to Holt Castle, over a river in the night, with six men of a thousand which before were with him."21

(1) Hutchinson Memoirs, pp. 129-30.
(2) Gardiner: History of the Great Civil War. I., p. 191.
(3) Some were at Watnall and West Hallam. Felley was also occupied.
(4) Vicar's Parliamentary Chronicle. God's Arke, pp. 134-5.
(5) Journals of House of Commons, III., p. 164. Die. 30-1643. He held the office until October 25th, 1646, when Gilbert Armstrong of Rempston was appointed. Journals IV., p. 320 and List in Public Record Office.
(6) Rebellion, III., p. 698.
(7) See e.g., In Thomason Tracts E. 38 (4) The Military Scribe, March 12th-19th, 1644 ; E 38 (14) Mercurius Civicus March 14th-21st; Mercurius Britanicus March 18th-25th (In Nottingham City Library).
(8) Britain's Remembrancer March 19th-26th (Thomason Tracts E. 39 (10), speaks of his troops as being drawn up " in such a place as neither policy nor prudence could persuade them unto." But Meldrum may have had some prospect of relief from Manchester; and the Committee of Both Kingdoms wrote to the Earl on March 22nd— before Rupert's victory was known in London—urging him to " do everything that may conduce to the safety of those forces (i.e., before Newark). ... If your forces come timely Prince Rupert's army may well be in the same straits yours now is conceived to be " (Cal. S. P. Dom., 1644, p. 66). The folly of expecting any prompt decisive action from Manchester had not yet been learnt.
(9) The parliamentarians numbered 1,500. Britain's Remembrancer March 19th-26th, (Thomason E. 39 (10). Rupert had hurried forward with his vanguard only, and we do not know how many men actually charged down Beacon Hill with him. But it is probable that he outnumbered his opponents, for some of the Lincolnshire horse bolted as soon as the battle was joined.
(10) This is confirmed by Britain's Remembrancer, March 26th— April 2nd. (Thomason E. 40 (11) ) which says " Colonel Thorneigh, a valiant gentleman, commanded that party which put the Prince to that distresse."
(11) See " A brief relation of the Siege of Newark, by Colonel Bury." (In the Nottingham City Library).
(12) Welbeck was garrisoned by the royalists early in 1643, and the neighbouring gentry had sent in their valuables for safe keeping. Newcastle's daughters were there, and remained so after it had changed hands. Judging by their letter of thanks to Lord Fairfax in April, 1645 (Fairfax Correspondence, I., pp. 194-5) the new governor. Colonel Thornhagh, treated them with the utmost consideration.
(13) Rushworth, V., p. 644. Journals of House of Commons, III., p. 692.
(14) Journals  of House of Commons, III., p. 714 ; Whitelock, I., p. 348.
(15) Hutchinson Memoirs, p. 218 ; Whitelock, I., p. 367.
(16) Cal. S. P. Dom., 1644-5, pp. 146, 172, 234.
(17) Brown: History of Newark, II., p. 79.
(18) Journals of House of Commons, IV, p. 258; Whitelock, I., p. 502.
(19) Whitelock, I., p. 521.
(20) Lord Gerard who commanded the royalist troops in South Wales.
(21) Quoted by Sir C. Firth in Hutckinson Memoirs, p. 230, note 3.