return from his travels early in 1764, Macartney was considered one of the handsomest and most accomplished young men of his day. Fox's father, Lord Holland [see Fox, Henry, Lord Holland], proposed that Macartney should enter the House of Commons as member for Midhurst. Instead, he was appointed, 22 Aug. 1764, envoy-extraordinary to St. Petersburg, to conclude a commercial treaty with Russia. Before starting he was knighted (19 Oct. 1764). After a long and difficult negotiation he accomplished his task to the satisfaction of both courts, and received the Polish order of the White Eagle. Charles James Fox eulogised his address to the Empress Catherine: ‘I think your speech to the Czarina one of the neatest things of the kind I ever saw; and I can assure you Burke admires it prodigiously.’ Returning to England in June 1767, Macartney declined an offer of the embassy at St. Petersburg, and next year married a daughter of Lord Bute. He was returned to parliament for Cockermouth, but resigned when elected for Antrim in the Irish House of Commons, in view of his becoming chief secretary for Ireland—a post to which he was appointed 1 Jan. 1769, and held until 1772, when he was made K.B. As leader of the ministerial side in the Irish house, he was noted for his good temper and firmness in dealing with the opposition, led by Henry Flood [q. v.], Dr. Charles Lucas (1713–1771) [q. v.], and others. In 1774 he was made governor of Toome Castle, a sinecure worth 1,000l. a year, which he sold to pay debts contracted during his embassy to Russia.
In 1775 Macartney was appointed captain-general and governor of the Caribbee islands (Grenada, the Grenadines and Tobago), and in 1776 was raised to the Irish peerage as Baron Macartney, of Lissanoure. He was on his post at Grenada in 1779 when that island was attacked, and after a gallant defence was captured by the French (cf. his papers in Brit. Mus. Egerton MS. 2135 ff. 54–72). Macartney was carried as a prisoner of war to France, but was soon exchanged. In 1780 he was sent by Lord North on a confidential mission to Ireland, and sat for a while in the English commons as member for Beeralston, Devonshire. The East India Company having decided in November 1780 that other than company's servants should be eligible for Indian governorships, Macartney was proposed and appointed governor and president of Fort St. George (Madras). He arrived at Madras on 22 June 1781, bringing news of the war with the Dutch, and hearing for the first time that Hyder Ali had invaded and overrun the Carnatic. He seized the Dutch ports of Sudras and Palicut; the Dutch settlements at Negapatam and Trincomalee were captured by the naval squadron under Sir Edward Hughes [q. v.] Macartney followed up the brilliant victory of Sir Eyre Coote (1726–1783) [q. v.], at Porto Novo, 1 July 1781, by overtures to treat with Hyder, who returned a characteristic reply (see Mill, iv. 221), and with the Mahrattas. Macartney treated Coote with deference and courtesy, and appears to have had a sincere regard for him; but Coote was ill and captious, and resented Macartney's policy of subordinating the military to the civil power, which he carried to extremity throughout his tenure of government, and pressed as an essential on the directors after his return home. Coote was supported by Warren Hastings and the Bengal council, whose control Macartney opposed. When Coote's failing health compelled him to return to Bengal, Macartney declined to allow the same latitude to his successor, Major-general James Stuart. On hearing of the death of Hyder—knowing the want of cohesion in eastern armies, and rightly estimating the chances of their dispersion if vigorously attacked at such a time—Macartney urged immediate action; but Stuart was too busy with his own grievances to enter warmly into these views. After Stuart's mismanagement of the expedition for the recapture of Cuddalore, and various acts of disobedience, Macartney caused him to be arrested and sent him home. Macartney drew up a treaty with Hyder's successor, Tippoo Sahib, which was approved by the Bengal council during the absence of Warren Hastings at Lucknow. But Macartney subsequently received a revised text of the treaty, altered so as to include the nabob of Arcot, whose territory was to be restored. Macartney strongly opposed this measure, and, on learning that his views were not upheld at home, sent in his resignation. He visited Calcutta on his way home, in a vain attempt to impress his views on the Bengal government, and was detained there by a long and dangerous illness. Before leaving he received a despatch from the board of control, offering him the post of governor-general in succession to Hastings. He arrived in England in January 1786. Except in regard of the nabob of Arcot, his acts were warmly approved both by the court of directors and by Pitt. Macartney refused the governor-generalship, which ultimately was given to Lord Cornwallis. The East India directors presented him with a piece of plate of the value of 1,600l., for the forbearance and justice of his conduct at Madras,