Prince Charles had offered to marry the infanta of Spain, and when the scheme of the Spanish marriage was abandoned, Herbert was entrusted with the embarrassing task of opening negotiations with the French government for Charles's marriage with Princess Henrietta Maria. James I was desirous that France should intervene in the German strife in behalf of his son-in-law the elector palatine, and directed Herbert to make that intervention a condition of the union. Herbert rightly pointed out that Louis XIII was very unlikely to accept such terms. Herbert's attitude offended the king, and in April 1624 he was suddenly dismissed. Before leaving Paris he printed there his treatise ‘De Veritate.’
Herbert came home in July deep in debt. He claimed to have ‘lived in a more chargeable fashion’ than any of his predecessors, and remittances from England had been irregularly paid. He pressed in vain for a settlement of his accounts. His only reward in the first instance was the Irish peerage of Castleisland, county Kerry, from the name of an estate inherited by his wife (30 Dec. 1624). He was promised an English peerage later. On 8 May 1626 he petitioned Charles I for payment of his debts, for an English peerage, and for seats in the privy council and council for war. His pecuniary embarrassment was growing, but he received a joint grant with his brother George and another of the manor of Ribbesford, 21 July 1627 ; on 7 May 1629 was created Lord Herbert of Cherbury or Chirbury (the name of an estate of his in Shropshire) in the English peerage ; and on 27 June 1632 was appointed a member of the council of war, to which he was reappointed 29 May 1637. To improve his position with the king, he wrote after Buckingham's death a vindication of Buckingham's conduct at La Rochelle in 1627, in reply to pamphlets by a Frenchman named Isnard and a jesuit named Monat, and on the basis of notes prepared by Buckingham himself. The book, which was only circulated in manuscript, was dedicated (from Montgomery Castle, 10 Aug. 1630) to Charles. It was commended by Sir Henry Wotton (Reliquiæ Wotton. 1685, p. 226), but gained no royal recognition. In 1632 he began his great historical work on the reign of Henry VIII, and in the next year applied to the crown for pecuniary aid in prosecuting his researches. He was granted apartments in the palace at Richmond, but on 10 Jan. 1634-5 begged to be allowed to remove to Whitehall or St. James's Palace, in order to have ‘access to the paper chamber of the one and the library of the other house.’ He sought (he wrote at the same time) some unequivocal mark of royal favour in order to be distinguished from Sir Thomas More or Bacon, ‘great personages,’ who had devoted themselves to historical work ‘in the time of their disgrace, when otherwise they were disabled to appear’ (Cal. State Papers, Dom., 17 Jan. 1634-5). On 14 March 1635 he sent Charles I a paper of observations on the necessity of vesting the supremacy of the church in the ruler of the state, and the king sent the document to Laud, with whom Herbert was on familiar terms. But in his yearning for praise from whatever quarter it might come, he informed Panzani, the papal envoy at Charles I's court, a month or two later, that in his history of Henry VIII he intended to favour the theories of the papacy, and offered to submit his philosophical treatise ‘De Veritate’ to the pope's criticism. With characteristic versatility he was interesting himself in mechanical invention at the same time, and sent to Windebank in 1635 suggested improvements in warships and gun-carriages, and proposed the erection of a floating bathing-palace on the Thames (ib. 1635, pp. 62-3).
When summoned to attend the king at York on the expedition into Scotland in 1639, Herbert in reply rehearsed at length all his grievances, and mentioned that he was harassed by lawsuits. But in accordance with his promise he attended the king after a short delay. At Alnwick he wrote a poem on the expedition. In the autumn of 1640 he attended the king's council, and argued strongly, but without any effect, against purchasing any treaty of peace with the Scots (Rushworth, ii. 1293). After spending the following year among his books at Montgomery Castle, he came up to the House of Lords in May 1642. In the discussion on the commons' resolution that the king transgressed his oath if he made war on parliament, Herbert argued for the addition to the latter clause of the words ‘without cause,’ a suggestion which offended the commons, and led to his committal to the Tower; but he made a handsome apology, and was soon released. He returned to Montgomery Castle, and contemplated a visit to Spa for his health. His sons were actively engaged with the royalist army in the civil wars, but Herbert resolved as far as possible to play a neutral part. In letters written to his brother, Sir Henry, in August 1643, he showed much resentment that the war should, by approaching Wales, threaten him with personal discomfort, but evinced no interest in the great issues at stake. Herbert declined the summons to attend Charles I at Oxford on the ground of ill-health, and when Prince Rupert, for whose mother he had declared in earlier life
