MONTAGU, WALTER (1603?–1677), abbot of St. Martin's, near Pontoise, was the second son of Sir Henry Montagu, first earl of Manchester [q. v.], by his first wife, Catherine, second daughter of Sir William Spencer of Yarnton, Oxfordshire. Edward Montagu, second earl of Manchester [q. v.], was his brother. Born in the parish of St. Botolph without Aldgate, London, in or about 1603, Walter was admitted on 27 Jan. 1617-18 a fellow-commoner of Sidney Sussex College, Cambridge. On leaving the university he went abroad to improve himself in modern languages 'and other qualifications proper for a nobleman.' On his return he was well received at court, and was employed by the Duke of Buckingham, who sent him on a secret mission to France in 1624, when the marriage with the Princess Henrietta Maria was first in contemplation (Hardwicke, State Papers, i. 465). In March 1624-5 Buckingham was 'preparing for France,' as 'Wat Montagu brings word that all is forward, and the lady shall be delivered in thirty days.' Montagu, who was rewarded with 200l. for this 'special service,' thus formed a friendship with Henrietta Maria, which ended only with his life. In 1625 he was again despatched to France on business connected with her arbitrary seizure of some English vessels, and on his return in January 1625-6 he brought with him a promise of restitution of our ships, and an assurance that peace was about to be concluded by the French government with the protestants.
In 1627 he graduated M.A. at Cambridge as a nobleman's son (Wood, Fasti Oxon. ii. 284 n.); and in the same year he was sent to Lorraine and Italy to stir up discontent against France, but he met with little encouragement. In October he reported to Charles I that in case of a continental war he would have no allies. Shortly afterwards an officer commissioned by Richelieu suddenly arrested him as he was passing through Lorraine, and, in spite of the protection of neutral territory, carried him and his despatches to Paris, where he was lodged in the Bastille. He soon regained his liberty, however, as he was present at the assassination of the Duke of Buckingham at Portsmouth in August 1628. Later in that year he went abroad to negotiate with Richelieu an exchange of prisoners. In March 1631 the sum of 1,100l. was paid to him 'for his Majesty's secret service in France,' with an additional 400l. 'for his charges in his journey.' He did not return permanently to England till 1633.
Subsequently he was residing in Paris as attaché to the British embassy, when out of curiosity he went to Loudun to witness the exorcisms of the Ursuline nuns, which were then the talk of all France. What he witnessed led him to become a catholic, and in July 1635 he arrived in London to announce his departure for Rome and his intention to join the fathers of the Oratory. It appears that he finally made his abjuration in the hands of the pope himself (Foley, Records, v. 606). His conversion became a matter of gossip at the court, and the letter in which he announced it to his father, the Earl of Manchester, passed from hand to hand (Gardiner, Hist. of England, viii. 139).
Afterwards he was allowed to return to England, though he was received more warmly at Somerset House, the queen's residence, than at Whitehall, and he zealously seconded Father Con's efforts to induce the queen to take an active part in the propagation of the Roman catholic religion. He also acted in April 1639 with Sir Kenelm Digby [q. v.] as her majesty's agent in collecting a contribution from the catholics towards defraying the expense of the royal army. In 1641 the House of Commons ordered him, Sir John Winter, the queen's secretary, Sir Kenelm Digby, and two other catholic gentlemen, to give an account of their part in the collection of this contribution. Various entries in the 'Journals' of the two houses indicate his activity in the support of the royal cause. He was obliged to retire to France, taking with him a strong recommendatory letter from the queen (Green, Letters of Henrietta Maria, p. 38) . In March 1642-3 a letter in cipher from the king to Montagu was intercepted in Bedfordshire, and in October 1643 Montagu was apprehended at Rochester, brought up to London, and ordered by the House of Commons to be detained as a close prisoner in the Tower (Commons' Journals, ii. 1005, 1007, iii. 260; Green, Letters of Henrietta Maria, p. 228). It appears that he had upon him letters sealed with the arms of France, and directed to both their majesties of England. On 9 Feb. 1643-4 it was resolved by the commons that all his goods should be seized and sold for the use of
