Lord Forbes was closely connected with the 2nd Duke of Argyll, to whom he owed his military career and whom he followed politically. Holding commissions both in the army and the navy, he served with distinction in the war of the Spanish succession, taking part in several land actions. Meanwhile, in 1717, after Argyll had dissuaded him from buying the 4th troop of Horse Guards from Lord Dundonald for 10,000 guineas, he retired from the army in order to concentrate on his naval career. In the same year his father made over to him all the family estates in return for a pension of £700 and the payment of certain annuities. In 1719 the Emperor, whom he had known as the Archduke Charles during the Spanish succession war, summoned him to Vienna to build a navy based on Trieste. Forbes, however, ran into opposition from the imperial ministers and resigned this appointment after two years. Brought in by the Government for Queenborough at a by-election in 1723, he served afloat in the Mediterranean, 1726-7, and again for the last time in 1731. From 1729 to 1731 he was nominally governor of the Leeward Islands, but never went there, on the ground that the refusal of the local assemblies to vote him a fixed salary would leave him ‘at the mercy of those whom he was to govern by instructions from the King’. In 1733 he went to St. Petersburg to conclude a trade treaty, making such a good impression on the Empress Anna that she later offered him the command of the Russian navy, which he rejected. In 1738, now Lord Granard, he refused the governorship of New York, apparently because his friends were unable to obtain for him the order of the Thistle. According to his son, Walpole disliked him, ‘giving for reason that he was a man too curious and busy’.
He died 19 June 1765.
