Sir Richard, a distinguished cavalier in the heroic age of the civil wars and the protectorate, was the youngest son of Sir Henry Fanshawe, brother of Lord Viscount Fanshawe of Dromore in Ireland, and born at Ware-park, Hertfordshire, in June 1608. He had only attained his seventh year at the time of his father's death, when the care of his education devolved on his mother, who placed him under the celebrated schoolmaster Thomas Farnaby, and, in due time, sent him to Cambridge, where he was admitted as a fellow-commoner of Jesus College in November 1623. Having prosecuted his studies with success, and, in particular, discovered a taste for classical learning, he was, in January 1626, removed to the Inner Temple; but at his mother's death, which happened soon afterwards, he resolved to pursue a line of life more congenial to his inclination, and, with this view, he visited France and Spain, where, in the course of his travels, he acquired the languages and studied the manners and institutions of those countries. On his return to England he was appointed secretary of legation to the embassy at Madrid, whither he immediately repaired, and was left as chargé d'affaires at the Spanish court from the time of Lord Aston's resignation till the appointment of Sir Arthur Hopton as his successor in 1638.

On the breaking out of the civil war, Fanshawe, being then in England, declared at once for the king, and was entrusted with several important employments. In 1644, whilst attending the court at Oxford, he was made secretary to the Prince of Wales, whom he accompanied in his expedition to the western parts of England, and thence to the islands of Scilly and Jersey. In 1648, he was appointed treasurer of the navy under Prince Rupert, an office which he held till 1650, when he was created a baronet, and sent to Madrid to represent the necessitous condition of the king his master, and to implore assistance from Philip IV. Recalled to Scotland, where Charles II. had now made his appearance, he served there in the capacity of secretary of state, but without taking either the covenant or the engagement; and being recommended by the king to the York party, he was received with great kindness by the latter, and entrusted with the broad seal and signet. In 1651, Sir Richard was taken prisoner at the battle of Worcester, conveyed thence to London, and there committed to close custody; but having contracted a dangerous illness, he was liberated on giving bail to the amount of four thousand pounds, chiefly, as would appear, through the intercession and influence of Cromwell. In 1654, we find him at Tenterley park, which he had hired of his friend Lord Strafford, to whom he dedicated his translation of the Lusiad of Camoens, written during his residence there. Early in 1659, he obtained the discharge of his bail, on pretence of going abroad with the eldest son of the Earl of Pembroke, and immediately repaired to Breda, where Charles II. received him with open arms, knighted him, and appointed him master of requests and Latin secretary.

On the restoration, Sir Richard expected, from a promise which had been formerly made to him, to be appointed secretary of state; but, through the paramount influence of Monk, Duke of Albemarle, the office was conferred on a creature of his own, Sir William Morrice. "The king," says Lady Fanshawe, in her Memoirs, "promised Sir Rich- Fanshawe, and that he should be one of the secretaries of state, in the event of his restoration, and both the Duke of Ormond and Lord Chancellor Clarendon were witnesses to it; but that false man (Monk) made the king break his word for his own accommodation, and placed Mr Morrice, a poor country gentleman of about L200 a year, a fierce presbyterian, and one who never saw the king's face; but still promises were made of the reversion to Sir Richard. In the parliament which met on the 8th May 1661, he took his seat as one of the representatives of the university of Cambridge, and was soon afterwards sworn a privy counsellor for Ireland. He was then sent as envoy extraordinary to Portugal; and being shortly afterwards appointed ambassador to the court of that country, he negotiated the treaty of marriage between Charles II. and the Infanta Donna Catharina, daughter of John VI. and returned to England towards the close of the year. In 1662 he was again sent as ambassador to the court of Lisbon, and, on his return to England the following year, was sworn a member of the privy council. Being considered by the king of Portugal as the fittest person to bring about an accommodation between that country and Spain, Sir Richard was, in the beginning of 1664, sent as ambassador to the court of Philip IV., by whom he was received with the most flattering marks of distinction, under the impression, as appears, that he was authorized, on the part of England, to give up Tangier and Jamaica to Spain. The Spaniards, however, finding themselves disappointed in this expectation, altered their tone; and cordiality having given place to coldness and distrust, the ambassador found himself exposed to frequent mortifications, and involved in the greatest perplexities. At the earnest desire of Spain he had made a journey to Lisbon, for the purpose of endeavouring to bring about an accommodation with Portugal, but returned without effecting any thing. At length, however, when the life of Philip IV. appeared to be drawing towards a close, a project of a treaty, containing greater commercial advantages, and insisting on fewer inconvenient conditions, than any that had formerly been proposed, was suddenly submitted to him, accompanied with an urgent demand of immediate acceptance or rejection, on account of the king's illness, which, it was alleged, might be followed by an entire change in the Spanish councils. In this emergency, the ambassador, after comparing the project with his instructions, and suggesting certain additions and modifications, which were agreed to, consented to sign the treaty, to which was annexed a secret article respecting Portugal, and immediately transmitted it to England. But objections having been taken to it in council, chiefly on the ground that the ambassador had exceeded his powers, the king was advised to withhold his ratification, and Sir Richard was in consequence recalled. But whilst he was preparing to return home, he was, on the 4th of June 1666, seized with a violent fever, which put an end to his life, at Madrid, on the 16th of the same month, the very day on which he had intended to take his departure for England.

Sir Richard Fanshawe was married in Wolvercot church, near Oxford, on the 18th May 1644, to a daughter of Sir John Harrison, by whom he had six sons and eight daughters, of whom only one son and four daughters survived him. Lady Fanshawe was related to her husband, inasmuch as her mother was daughter to Robert Fanshawe, Esq. of Fanshawe-gate, grand-uncle to Sir Richard. She is also the author of Memoirs which she composed for the use of her only surviving son, and which, besides many traits of natural feeling and noble sentiment, contain a very interesting account of the losses and sufferings of the Fanshawe family in the royal cause, and more particularly of the proceedings of her husband, Sir Richard, to whom she seems to have been most affectionately attached, and of whom, from the time of their marriage, she was the constant companion, amidst all the difficulties and perils of those troubled times. For a very judicious and discriminating notice of these Memoirs the reader is referred to the Edinburgh Review (vol. I. p. 75.)

Although much of Sir Richard Fanshawe's life was spent in active employment, he found leisure to produce the following works: 1. An English translation, in verse, of Guarini's Pastor Fido, 1646, in 4to.; 2. A translation from English into Latin verse of Fletcher's Faithful Shepherdess, 1658; 3. An Ode on the king's proclamation in 1630, an English translation of the fourth book of the Æneid, Odes of Horace translated into English, and a Discourse of the Civil Wars of Rome, inserted in the octavo edition of the Faithful Shepherdess; 4. A translation of the Lusiad of Camoens, 1655, in folio; 5. Two pieces, entitled, Querer per solo querer, published after his decease, 1671, in 4to., and Fiestas de Aranjuez, both written by Antonio de Mendoza in 1623, and translated into English by Sir Richard in 1654; 6. Correspondence, entitled Original Letters of his Excellency Sir Richard Fanshawe, during his Embassy in Spain and Portugal.