Accordingly on the 20th September, in the morning, the Prince put himself at the head of the army at Dudingston, and presenting his sword said—‘My friends I have flung away the scabbard.’ This was answered by a chearful huzza.
The army marched till they gained the top of Carberryhill, from whence we observed the enemy drawn up on the plain below, in order of battle. We continued the march along the brow of the hill, till we were opposite to the front of, and at half a miles distance from the enemy. Here the Highlanders gave a shout, by way of defiance, and nothing less than authority could restrain them from coming immediately to action.
Several officers were sent, particularly Colonel Ker of Gradane, to reconnoitre the enemy’s camp. They reported that General Cope had got into a fastness, where it was impossible to attack him, without risking the loss of the whole army: That his right was drawn up to the high walls of the gardens of Preston, where he had made several breaches to retire into, if needful: The house of Seton and a small morass on the left: An inclosure not half a gun shot over, surrounded with a ditch three or four feet deep, and five or six broad, covered his front; which made two ditches of that breadth and depth to pass: And the sea was in his rear, at no great distance from him: His canons and coehorns were planted on a high way that led to Tranent, between the above inclosure and morass. Thus his front was to the south, his rear to the north, his right to the west, and his left to the east.
In this situation what was to be done? It was about two o’clock in the after-noon. The Prince made several movements to amuse the enemy, and placed guards on the several roads that led to their camp. In the mean time General Cope discharged several canon at us, but without effect.
At twilight the Prince drew off his men, and marched to Tranent. From hence he detached Lord Nairne, with 500 men, to guard the road that led from Preston to Edinburgh, to prevent Cope from marching thither. On the other hand General Cope, afraid that the Prince should have directed his march eastwards, altered his disposition, and faced east, having now the morass in front; and his troops were thus disposed. General Hamilton’s dragoons were on his right, and Colonel Gardiners on his left. The regiment of Lascelle’s and Murray, with five companies of Lees and four of Guises formed the center. And his second line consisted of three companies of the Earl of Loudun’s regiment, two of Lord John Murray’s, a body of Monros, and a great number of recruits for regiments abroad. Amounting in all to about 2000 foot, and 700 dragoons.
As it was now dark, the Prince ordered the army to march and to take possession of the ground on the south east of the morass which they did, at about half canon shot of the enemy. We continued under arms in the order of march, observing the greatest silence, so that Cope did not perceive where we were.
About three o’clock of the morning of the 21st, orders were sent to Lord Nairne to draw off his guards and join the Prince, which he immediately did. The disposition of the attack being made, the Prince addressed his army in these words—‘Follow me, gentlemen, by the assistance of God, I will this day make you a free and happy people.’ The right wing was commanded by the Duke of Perth, Lieutenant General, and consisted of the Macdonalds of Clanranald, Glengary, Keppoch and Glenco, and Grants of Glenmoriston. The left wing was commanded by Lord George Murray, Lieutenant-General, and consisted of the Camerons of Lochiel, Stuarts of Appin, and two companies of Macgregors. The second line was commanded by Lord Nairne, Major-General, and consisted of Athole-men, Robertsons of Strouan, Maclauchlans, and the Duke of Perth’s men. About 25 gentlemen, and their servants, a horse-back, formed a sort of corps de reserve. The whole army consisted of about 2200 men.
We marched chearfully on. The Duke of Perth was conducted by a gentleman, of the name of Anderson, by a ford through the above morass; where 100 men could have prevented our passage: it was so difficult that every step the men made they sunk to the knee in mud. This made them pass in some disorder, but not being observed, by means of the darkness, they formed again as they passed the morass. But the Duke of Perth, in place of inclining to the enemy’s left, to avoid being seen by them before all our men were passed, marched towards the sea: so when our left gained the plain, Lord George Murray found that he was nearer the enemy than the Duke of Perth was. However, day beginning to break the attack was ordered.
The highlanders, pulling off their bonnets and looking up to heaven, made a short prayer, and ran forward. In advancing Lord George Murray observed, that by the turn of the morass, there was a great interval between his left and the ditch of the before mentioned inclosure: he therefore ordered the Camerons to incline that way, in order to take it up, to prevent being flanked by the enemy’s dragoons. By this movement there became a considerable interval in the center, which the 2d line was ordered to fill up. We were now discovered by the enemy, who played their artillery furiously upon our left; yet only one private man was killed, and one officer wounded. The highlanders ran on with such eagerness that they immediately seized the canon. The dragoons on right and left made a very regular fire, which was followed by close platoons of all their infantry, which our men received with great intrepidity. But what by the huzzas of the highlanders, and their fire which was very brisk, the dragoons were immediately thrown into disorder, which occasioned some confusion among their foot. The highlanders threw down their muskets, drew their swords, and carried all before them like a torrent: so that in seven or eight minutes both horse and foot were totally routed, and drove from the field of battle.
The Prince during the action was on foot in the 2d line. He was with great difficulty prevailed on not to attack with the first line in so much that the officers refused to march if he insisted on it. As soon as the victory declared for him, he mounted his horse and put a stop to the slaughter, calling out,—‘make prisoners: spare them, spare them, they are my father’s subjects.’