[7] The Royalists had intended to send the king's nephew and foremost field commander, Prince Rupert, to the northwest to retrieve the situation early in 1644.

It became even more important to regain the northwest when the Fairfaxes and a Scottish Covenanter army began the Siege of York on 22 April.

As Rupert lacked the strength to proceed immediately to relieve York, it was agreed at a council of war in Oxford, the king's wartime capital, that he would first move into Lancashire to restore Royalist fortunes, use the Earl of Derby's influence to gather fresh recruits, and secure the port of Liverpool to allow communications with Royalist forces in Ireland.

He added Byron's army from Cheshire and North Wales to his own small force, giving him a total of 2,000 cavalry and 6,000 infantry.

[3] Late on 28 May, as Prince Rupert approached Bolton, he sent Colonel Henry Tillier, his quartermaster-general, with a regiment of horse (cavalry) and another of foot (infantry) to secure the town.

[12] He made his way to the Parliamentarian and Covenanter "Army of Both Kingdoms" besieging York, where he claimed that 1,500 of his total force had been poorly armed clubmen.

He also claimed that he lost only 200 men, the rest of his forces having fled, but the commanders of the armies around York noted that "vulgar reports" were that they had been slaughtered.

Unlike a formal siege, usually preceded by parleys and often ended at some point by a negotiated surrender, Rupert attacked suddenly to catch the Parliamentarians in temporary disarray.

At least two of the attacking Royalist regiments (Warren's and Broughton's) had been raised in England in 1640 to serve in the Bishops' Wars but were sent to Ireland after the Irish Rebellion of 1641.

At midday on 10 June, having made breaches in the earth walls with cannon fire, the Royalists launched an assault which was beaten back.

During the following night, the Parliamentarians abandoned the town and left aboard ships in the harbour, leaving their colours on the remains of the walls as a ruse.

[14] When Colonel Henry Tillier's regiment (another unit recently returned from Ireland) advanced into the town the next morning, they found 400 remaining defenders "of the meaner sorte", many of whom were killed, only some being given quarter.

Meldrum spared the garrison, including soldiers returned from or recruited in Ireland, despite a Parliamentarian ordinance of no quarter to the Irish.

However the parish register of the town gives the names of only seventy-eight individuals, noting "All those of Botonn slayne on the 28 of May, 1644", which seems to imply that the list is comprehensive.

Perhaps more significantly, all three individuals mentioned as murdered in the anonymous parliamentarian eyewitness account published three months later were also named in the register.