The victorious insurgents took Dundalk and began to lay siege to Drogheda. The Lords Justices in Dublin Castle announced the existence of

'a most disloyal and detestable conspiracy by some evil-affected Irish papists.'

The Catholic Old English gentlemen had responded to the Dublin government’s call to arms. As they marched north to Drogheda, however, they wondered whether they, too, were being branded as ‘disloyal and detestable’. For years they had been persecuted on account of their religion and, despite their long record of loyalty to the Crown, they had been threatened with the confiscation of their lands.

As they approached the walled town, they turned aside near the Hill of Tara. There, in December 1641, they had a meeting with the Gaelic Irish commanders. The momentous decision they arrived at was to join the native Irish rebels of Ulster. For centuries these Old English lords, descendants of the Norman conquerors, had fought loyally for the English government. Now they had been pushed too far. Richard Bellings, who had been at the meeting, knew how significant it was:

'And thus, distrust, aversion, force, and fear united the two parties which since the conquest had at all times been most opposite, and … publicly declared that they would repute all such enemies as did not assist them in their ways…'

Protestant refugees from the surrounding countryside poured into Drogheda. One defender reported:

'Miserable spectacles of wealthy men and women, utterly despoiled and undone, nay, stripped stark naked, with doleful cries, came flocking in to us by multitudes, upon whom our bowels could not but yearn.'

Help came in the spring of 1642. The Westminster Parliament had voted to rush troops to Ireland. The Duke of Ormond brought over a large English army and sent troops from Dublin to relieve Drogheda. His officer commanding reported:

'The number of the slain, I looked not after, but there was little mercy shown in those times.'