in support of Lord John Russell's bill for the removal of the disabilities of the Jews (4 May 1848), and published a pamphlet with the title 'Christian Profession not the Test of Citizenship.' He opposed the ridiculous penal measure passed in consequence of the so-called papal aggression (21 March 1851), and the subsequent agitation for the withdrawal of the Maynooth grant and the subjection of religious houses to inspection (25 May 1852, 23 Feb. 1853, 28 March 1854). He took office for the first time under Lord Aberdeen, when he served as junior lord of the treasury (March 1854-March 1855). He was under-secretary of state for the colonies under Palmerston (1857-8), and again from Palmerston's return to power in June 1859 until the reconstruction of the administration which followed that statesman's death in October 1865. In the meanwhile he had been sworn of the privy council (7 April 1864). In November 1865 he succeeded Sir Robert Peel (1822-1895) [q. v.] as chief secretary for Ireland on the formation of Lord Russell's ministry.
Fortescue entered the Irish office at a critical epoch. The Fenian insurrection had been crushed, but the forces of disaffection were still energetic underground. The policy of the government was to apply the healing balm of remedial legislation. An attempt had been made in 1860 to improve the relations between landlords and tenants by an act which conferred certain powers on limited owners, but the measure had remained a dead letter (23 and 24 Vict. c. 153). Fortescue now introduced a bill to enlarge the powers of limited owners, and secure to tenants compensation for their improvements. The measure was, however, thrust into the background by the parliamentary reform bills ; their defeat was followed by the resignation of ministers (26 June 1866), and Fortescue's Irish land bill was withdrawn. He resumed the Irish secretaryship on the formation of Gladstone's first administration (December 1868), and shared with Gladstone the burden and the credit of the two great reforms which followed, the disestablishment of the Irish church and the extension of the Ulster custom, with compensation for improvements, to the whole of Ireland. The details and even the principles of this land act of 1870, which John Stuart Mill described as the most important measure passed by the British parliament since the Roman Catholic Emancipation Act, were almost entirely the outcome of Fortescue's judgment; but he had not the physical and oratorical powers necessary to carry such a measure through parliament, a task which Gladstone reserved for himself (Spectator, 1898, i. 198-199). The remedial legislation did not, however, dispense with the necessity for the enactment of a Peace Preservation Act during the same session of 1870. At the end of the year the situation in Ireland was thought to demand a statesman of greater weight at the Irish office. Accordingly Lord Hartington was appointed to that post, which Fortescue vacated, at the same time succeeding John Bright [q. v. Suppl.] as president of the board of trade (14 Jan. 1871). In his new capacity he deserved well of the public by the effective measures which he took to constrain railway directors to be more careful of the lives of their passengers. In general politics he still followed Gladstone unwaveringly, even supporting him on the Irish university question. At the general election following the dissolution of parliament in January 1874, he was rejected by his old constituency, co. Louth. He was at once (27 Feb. 1874) raised to the peerage as Baron Carlingford of Carlingford in the county of Louth. On the defection of the Duke of Argyll from Gladstone's second administration on the promise of a new Irish land bill, Carlingford accepted the privy seal (2 May 1881), and defended the Irish policy of the government in no hesitating or half-hearted manner. He took an important part in framing Gladstone's second Irish Land Act, and conducted it through the House of Lords. He succeeded Lord Spencer as president of the council on 19 March 1883, holding the privy seal with the office of president until March 1885. He retained the presidency of the council until the fall of Gladstone's government in June 1885.
Carlingford's views on the Irish question were based on an intimate knowledge of the Irish people, and matured by independent thought. He had been among the earliest advocates of the policy of conciliation, and his concurrence in the late developments of the Gladstonian policy had been unconstrained by party considerations. But he had never contemplated any tampering with the union, and he consequently declined to follow his old chief, Gladstone, in his espousal of the home rule cause in 1886. He joined the ranks of the liberal unionists, but spent his closing years in comparative retirement. He was president of the Liberal Unionist Association of Somerset, for which county he was a magistrate. He was also lord lieutenant of Essex (1873-92). He was K.P. (from 1882), and succeeded his brother as second Baron Clermont on 29 July 1887. By his death without issue at Marseilles, on 30 Jan. 1898, his honours became extinct.