Descended from an old baronial family, which was afterwards ennobled by the Earldom of Carnwath, and which acquired its estates about the end of the sixteenth century he was the son of Thomas Dalyell, of the Binns, in West Lothian, and of the Honourable Janet Bruce, a daughter of the first Lord Bruce of Kinloss, the eminent minister of James VI.--a peer whose skill in statecraft, in conjunction with the Earl of Mar, was of great service in securing James's peaceful accession to the English throne in 1603. Thomas Dalyell, the younger, is said to have been born about the year 1599, during the reign of James VI. in Scotland, at his father's house of Binns, in the parish of Abercorn, Linlithgowshire. The ancient name is Dalyell; but the _z_ has since crept in, by the corruption of the letter _y_ in old Scottish orthography, and hence the pronunciation of it so puzzling to an English tongue. Dalyell is first heard of as an officer of those auxiliary Scottish troops sent to Ireland by their native Parliament, at the request of Charles I., to protect the Ulster colonists, and assist in repressing the rebellion under Sir Phelim O'Neil and Macguire, when the dreadful massacre of the English took place. For this service the Parliament of Scotland levied eight battalions of infantry, of whom two thousand five hundred were Highlanders. Arms for three thousand men were offered to the Irish Protestants, and the castles of Craigmore and Carrickfergus, two small strongholds in the north of Ireland, were supplied with all requisite munitions of war from the magazines at Dumbarton. The colonels of the eight Scottish regiments which mustered in November, 1641, were as follow:-- Archibald, Earl of Argyle, afterwards executed for treason in 1660. Sir Duncan Campbell, of Auchinbreck, who was afterwards slain at the battle of Inverlochy. Sir Mungo Campbell, of Lawers. These three had Highland battalions. Alexander Lord Forbes, who had served the King of Sweden. William, Earl of Lothian. Alexander, Earl of Eglinton. Lord Sinclair. The Earl of Lindesay. Major-General Sir David Leslie, of Pitcairly, was to command the whole. Argyle deputed the leading of his regiment to its lieutenant-colonel, James Wallace, of Auchans; Lord Sinclair's was led by his major, Sir James Turner, the celebrated military memorialist, and that of the Lord Lindesay was led by Major Borthwick. Thomas Dalyell was an officer in these forces, but to which corps he was attached is not clearly known. He was with the first column of those auxiliaries which, under Major-General Munro--an officer who had long served with distinction in Germany, at the head of Lord Reay's Highlanders--embarked on the 2nd of April, 1642, for Ireland. He had with him three thousand infantry, six hundred cavalry, and a train of guns. Landing in the north of Ireland, he took possession of Carrickfergus, and in it placed a garrison under young Dalyell's command.