He was born in Glasgow, the son of Hugh Crawford of Kilbirnie and from a fairly early age served in the armies of Christian IV of Denmark, Gustavus Adolphus of Sweden and Charles I Louis, Elector Palatine.
Having travelled to England in the suite of Charles Louis, in 1641 Crawford was appointed Colonel of a regiment of foot which was to serve in Ireland in the army of the Earl of Ormonde to put down the Irish Rebellion of 1641.
He almost immediately clashed with the army's Lieutenant General, Oliver Cromwell, over the appointment of Independents as officers.
Parliament's agreement with the Scottish Covenanters, by which Presbyterianism was to be made the established religion of both countries meant that Crawford was legally in the right, but neither General would give way.
Crawford's foot regiments provided invaluable support to Cromwell's cavalry, who largely won the battle.