steward of Reading (Coates, Hist. of Reading, App.) Returning to his post at the Hague, he signed, on 4 Jan. 1716–7, the treaty of the Triple Alliance between Great Britain, France, and Holland. After attending George I on a visit to Hanover, the diplomatic duties at the Hague being meanwhile performed by Mr. Leathes, secretary at Brussels, Cadogan came to England with the king, and was sworn of the privy council on 17 March 1717, and on 12 July following was promoted to general ‘of all and singular the foot forces employed or to be employed in our service’ (Home Office, Mil. Entry Books, xi. 219). About the same time a vexatious indictment was brought against him in the lower house, in the shape of charges of fraud and embezzlement in connection with the transport of the Dutch troops to the Thames and Humber during the rising in the north. These were preferred by certain Jacobite members, to whom his success in Scotland had made him particularly obnoxious. The spiteful attack was urged with grotesque vehemence by Shippen, who was supported by Walpole and Pulteney, and opposed by Stanhope, Craggs, Lechmere, the new attorney-general, and others, and evidence in vindication of Cadogan was given at the bar of the house (see Boyer, Political State, i. 697–794). But the motion was only lost by a majority of ten. Cadogan resumed his diplomatic duties in Holland during the year, and, on his return home, 8 May 1718, he was elevated to an earldom, with the titles of Earl Cadogan, Viscount Caversham, and Baron Cadogan of Oakley, the last title with remainder, in default of male issue, to his brother Charles [see below]. After this he was again engaged at Brussels and the Hague in negotiations with the imperialist ministers and the Dutch representatives relative to the working of the (third) barrier treaty. Writing to Lord Stair, under date 10 March 1719, Lord Stanhope says: ‘Good Lord Cadogan, though he has made the utmost professions of friendship and deference to other people's measures, has certainly blown the coals; he has a notion of being premier ministre, which I believe you will with me think a very Irish idea’ (Hist. MSS. Comm. 2nd Rep. 189). In February 1720 Cadogan was despatched to Vienna with final instructions (dated 20 Feb. (old style) and superseding earlier instructions of 24 Nov. (o.s.) 1719) to treat with the Austrian court of northern affairs and of the Barrier Treaty.
Upon the death of the Duke of Marlborough in June 1722, Cadogan succeeded to the post of master-general of the ordnance. He became colonel of 1st foot guards from 18 June 1722; and was appointed a commissioner of Chelsea Hospital. His detractors accused him of appearing at Marlborough's funeral pageant indecorously dressed and betraying his want of sympathy by his looks and gestures. This was probably a malicious invention; but it gave the point to some savagely sarcastic lines by Bishop Atterbury, which are quoted by Horace Walpole (Letters, vii. 230). Atterbury having heard that at the time of his committal to the Tower Cadogan had declared that he ought to be flung to the lions, retorted in a letter to Pope with the lines describing Cadogan as ‘ungrateful to th' ungrateful man he grew by, A big, bad, bold, blustering, bloody, blundering booby.’ The year that witnessed the death of Marlborough saw likewise a revival of the Jacobite plots, including schemes for tampering with the Tower garrison and seizing on the Tower and Bank. Apprised of these projects, the government prevailed on the king to postpone an intended visit to Hanover, and to retire to Kensington Palace, an encampment of the whole of the guards being formed for his protection close by, in Hyde Park, under the personal command of Cadogan. In November 1722 the camp was broken up. When the king embarked for Hanover, Cadogan was appointed one of the lords justices. The military records of his rule as commander-in-chief and master-general of the ordnance present little of interest. The chief event of his remaining years was his litigation with the widowed Duchess of Marlborough respecting a sum of 50,000l., which the duke at the time of his exile had entrusted to him to place in the Dutch funds. Cadogan, with the best intentions, had invested the money in Austrian securities, which at the time appeared more advantageous. These, however, had greatly depreciated, and the duchess, whose letters betray a querulous feeling towards Cadogan, having insisted on reimbursement, Cadogan, who had not applied the money to the specific purpose for which it was entrusted to him, was obliged to make good the deficiency at heavy loss.
In his early days at the Hague, Cadogan married Margaretta, daughter of William Munter, counsellor of the court of Holland, and niece of Adam Tripp of Amsterdam, by whom he had two daughters, the Lady Sarah, afterwards married to the second duke of Richmond, and the Lady Margaretta, who married Count Bentinck, second son of William, earl of Portland. The countess long survived her husband, and died at the Hague in October 1749, aged 75.
Cadogan died at his house at Kensington
