For the surer purging of that Achan, Charles, and to conciliate the party who deemed him the greatest cause of wrath of all, the king had to sign a false and disgraceful declaration that he was “afflicted in spirit before God because of the impieties of his father and mother”!  He was helpless in the hands of Argyll, David Leslie, and the rest:  he knew they would desert him if he did not sign, and he yielded (August 16).  Meanwhile Cromwell, with Lambert, Monk, 16,000 foot and horse, and a victualling fleet, had reached Musselburgh, near Edinburgh, by July 28.

David Leslie very artfully evaded every attempt to force a fight, but hung about him in all his movements.  Cromwell was obliged to retreat for lack of supplies in a devastated country, and on September 1 reached Dunbar by the coast road.  Leslie, marching parallel along the hill-ridges, occupied Doonhill and secured a long, deep, and steep ravine, “the Peaths,” near Cockburnspath, barring Cromwell’s line of march.  On September 2 the controlling clerical Committee was still busily purging and depleting the Scottish army.  The night of September 2- 3 was very wet, the officers deserted their regiments to take shelter.  Says Leslie himself, “We might as easily have beaten them as we did James Graham at Philiphaugh, if the officers had stayed by their own troops and regiments.”  Several witnesses, and Cromwell himself, asserted that, owing to the insistence of the preachers, Leslie moved his men to the lower slopes on the afternoon of September 2.  “The Lord hath delivered them into our hands,” Cromwell is reported to have said.  They now occupied a position where the banks of the lower Broxburn were flat and assailable, not steep and forming a strong natural moat, as on the higher level.  All night Cromwell rode along and among his regiments of horse, biting his lip till the blood ran down his chin.  Leslie thought to surprise Cromwell; Cromwell surprised Leslie, crossed the Broxburn on the low level, before dawn, and drove into the Scots who were all unready, the matches of their muskets being wet and unlighted.  The centre made a good stand, but a flank charge by English cavalry cut up the Scots foot, and Leslie fled with the nobles, gentry, and mounted men.  In killed, wounded, and prisoners the Scots are said to have lost 14,000 men, a manifest exaggeration.  It was an utter defeat.

“Surely,” wrote Cromwell, “it is probable the Kirk has done her do.”  The Kirk thought not; purging must go on, “nobody must blame the Covenant.”  Neglect of family prayers was selected as one cause of the defeat!  Strachan and Ker, two extreme whigamores of the left wing of the godly, went to raise a western force that would neither acknowledge Charles nor join Cromwell, who now took Edinburgh Castle.  Charles was reduced by Argyll to make to him the most slavish promises, including the payment of 40,000 pounds, the part of the price of Charles I. which Argyll had not yet touched.