Thousands of the Protestant refugees sought safety and protection in Royalist strongholds or attempted to leave Ireland and return to England and Scotland.

During the colonization of Ulster King Charles awarded English and Scottish loyalists such as the Stewarts with large tracts of escheated land under the condition that improvements be made and tenant settlers be brought over from England or Scotland.

Originally the unit was formed to protect the Laggan Valley in eastern Donegal along with the northwest portions of counties Tyrone and Derry.

[1][9] William Stewart served as the nominal leader of the Laggan Army in the beginning as he had greater seniority and landed interests than his brother.

Fairly quickly, however, Robert Stewart was selected for overall command based upon his extensive experience in the Thirty Years' War on the European continent.

This was partly due to Felim O'Neill's lack of military experience, but also the Irish soldiers' tendencies to attack British civilians and plunder their possessions rather than fight the enemy forces.

Support for the rebellion among the local Irish lords was weak in counties Donegal and Derry compared to the enthusiasm across the rest of Ulster.

Alternatively, he may have believed that he could defeat the Laggan Army and then conquer northwest Ulster including the undefended Royalist stronghold and port city of Londonderry.

Or perhaps Felim was caught in a trap and had no other alternative in that the eastern counties of Ulster were held by Sir Robert Monro, commander of a Scottish expeditionary force, who was sent to protect Protestant civilians.

[1][11][12] Carrying through with his decision, Felim joined forces with the MacDonnells of Antrim in early June and marched west toward Donegal with an army estimated to be as large as 6,000 foot and several hundred horse.

Also supporting Felim in the invasion of Donegal was Alasdair Mac Colla, the Scottish military officer who defected to the side of the Irish Confederates in early 1642.

Stewart chose to act, sending a small vanguard of sharpshooters partway across the field to attack the Confederates, goading them to react.