according to his own account, without pay. He returned to Scotland before 1630, and on 28 June in that year Charles I granted a letter of presentation in favour of ‘William Mercer, sone lawfull to Mr. Johnne Mercer, minister at Slaynes, to the parsonage and vicarage of the teyndis, &c., of the kirk and parochine of Glenholme,’ &c. Glenholme was a prebend attached to the Chapel Royal of Stirling, but there is nothing to show that Mercer ever occupied the post, although benefices were often conferred on those who held no orders in the church. About 1638 he seems to have served as an officer in Ireland, where he says in his ‘Angliæ Speculum’ that his ‘father's heir’ was ‘put to sword.’ It appears that his elder brother, Robert, master of the grammar school at Ellon in Aberdeenshire, having resigned his office in 1628, and settling in Ireland, as minister of Mullaghbrack, co. Armagh, was with his wife massacred in the Irish rebellion of 1641, leaving three young children. William subsequently obtained through the Earl of Essex a commission as captain of horse in the parliamentary army in England; and while in this service he published his first volume, ‘Angliæ Speculum,’ in 1646. One of the poems at the end of this work is a petition from Mercer to the lords and commons for arrears of pay, amounting to 900l.; and in the journals of the house reference is made more than once to ‘Capt. Mercer's petition for arrears.’ In 1646 he published elegies on the deaths of his patron, the Earl of Essex, and of his father-in-law, Sir Henry Mervyn, both of whom had died in that year, and about the same time he was promoted to be lieutenant-colonel. In May 1650 Mercer was back in Scotland, once more in the direst straits. The minutes of the general assembly, dated Edinburgh, 23 May 1650, state: ‘The Commission of the Generall Assembly, considering the necessitous condition of Lieutenant-Colonell William Mercer, sone to umquhill Mr. Johne Merser, minister at Slaines, doe referre him to the charitable supplie of the Presbyterie of Edinburgh.’ At the Restoration Mercer made vows of loyalty to the new monarch. In 1669, when Baron Truro was appointed governor-general of Ireland, Mercer issued ‘A Welcom … at his Royal entry into the Castle of Dublin.’ In 1672 he revisited Scotland, to arrange a marriage between his eldest son and the heiress of the barony of Aldie, and when the negotiations broke down Mercer raised an action of damages for breach of treaty (Decisions of Court of Session), and prepared a series of verses eulogising the judges of the court, and appealing for their lordships' favour. An autograph copy of this production, which was not printed, is preserved, with his signature attached, in the Advocates' Library, Edinburgh; the title runs: ‘A Compendious Companion of the Lives and Lawes of the Senators of Rome, with the Lives and Lawes of the Senators of the Colledge of Justice, Edingburgh, in familiar Lynes. By a Servant to Mars and a Lover of the Muses, Lievt Collll William Mercer, Edinburgh, 1673,’ 4to, 32 pp. Mercer lost his cause, and father and son returned to Ireland. Mercer was alive in 1682, when his ‘News from Parnassus’ was ‘printed by M. W. for the Author,’ with a dedication to Charles II. This pamphlet was issued in order to advertise a ‘big book,’ on which the writer states that he had been occupied for twenty years.
Mercer's writings are mainly valuable for their autobiographical details. The majority of his verses are mere doggerel, and display an inordinate self-conceit. Their titles are: 1. ‘Angliæ Speculum, or England's Looking-Glasse, devided into two parts: the First Part containing a Brief Description of these unnatural Wars in England, with some particular persons, fomentors thereof, discovered; the vast Expenses and the Glory of the famous City of London, in maintaining the Protestant Religion, and their Privileges displayed. The Second Part, consisting of several Speeches, Anagrams, Epigrams, Acrosticks, and Sonnets, &c., by C. W. Mercer,’ London, printed by T. Paine, &c., 1646, 4to. In some copies there is the simple title ‘Angliæ Speculum, or Englands Looking-Glasse. Devided into two parts. By C. W. Mercer. London, printed by Tho. Paine, MDCXLVI.’ 2. ‘An Elegie in Memorie and at the interring of the bodie of the most famous and truly noble Knight, Sir Henry Mervyn, paterne of all true valour, worth, and arts, who departed this life the 30 of May, and lyes interred at Westminster, Anno Do. 1646. London, printed by James Cox, 1646,’ a broadsheet. 3. ‘An Elegie upon the Death of the Right Honble., most Noble, worthily Renownend, and truly valiant Lord, Robert, Earle of Essex and Ewe, &c., His Excellency, late Lord General of all the Forces raised by the Parliament of England in Defence of the Protestant Religion, who departed the 14th of September 1646. London, printed by I. C., 1646,’ a broadsheet. 4. ‘A Welcom in a Poem, to his Excellency, &c., at his Royal entry into the Castle of Dublin’ (first title). ‘Verbum Sapienti, or Mercer's Muse-making Melody, in a Welcom to his Excellency John, Lord Roberts, Baron of Truro, &c. Dublin, printed by Josiah Windsor, 1669,’
