He was taken prisoner early in the Civil War, and after over two years of close imprisonment, agreed to accompany the Lord Deputy Lisle to Munster. After leaving Ireland he gained brilliant successes at sea over the Dutch. Prince tells a tale that is characteristic of him and of Cromwell. The seamen who had served under Monk had been told that they should receive their full pay as soon as the prizes were sold off, but were unreasonably impatient; and while Monk was actually at Whitehall putting their claims before the Protector, news was brought him 'that three or four thousand seamen were come as far as Charing Cross with swords, pistols, and clubs, to demand their pay. General Monk, thinking himself wronged in this, ran down to meet them, drew his sword, and fell upon them; Cromwell following with one or two attendants, cut and hew the seamen, and drove them before him.' Prince finishes the story with applause of the boldness that 'should drive such great numbers of such furious creatures as English seamen.' Later, Monk's command in Scotland resulted in a state of order and quietness then very unusual in that country.

Accusations of dealing unfairly with the Parliament in 1659 may be levelled against him with some justice, but how was loyalty possible to a household so divided against itself as were the rulers of the Kingdom? The Army and the Parliament were in bitter antagonism to each other, and Lambert's soldiers had shut the Parliament out of Westminster. The members of the Rump Parliament, the earlier 'secluded' members, the Presbyterians, the Independents under Lambert, the Royalists, and smaller parties, were all working for their own ends. When Monk marched south, a deputation was sent to meet him from the Council of Officers, ostensibly to make terms between their army and his, but also with the secret object of establishing an understanding between him and Fleetwood that would enable the latter to get rid of his friend and colleague, General Lambert. Meanwhile Lambert, jealous of Fleetwood, sent a private and friendly message to Monk by Major-General Morgan, who not only betrayed his party at Lambert's bidding, but betrayed that patriot as well, for at the same time that he gave the message, he also delivered a secret letter from Lord Fairfax, begging Monk to adopt a course which would have been fatal to Lambert. And the country as a whole was heartily sick of both factions.

Had Monk openly declared himself for the Stuarts, at the time that he first began to prepare for the Restoration, he would probably have imperilled the success of the whole scheme, and most certainly would have plunged the country again into the horrors of Civil War. When he did reveal his negotiations with the exiled Court at Breda, 'London would not have borne many days, or even many hours longer, the extreme tension it was then suffering—the City one way, Westminster the other way; Monk's army between them, and Fleetwood's wolves prowling all round, and ready to pour in.'

Apart from all else, tribute must be paid to Monk's marvellous skill in so ordering affairs that the Restoration was brought about almost without the cost of a drop of blood. During the winter of 1659, a far larger army than his own lay for many weeks a few miles to the south on the Border, sent there with the especial purpose of watching and if necessary attacking him. But Monk knew how to bide his time and to prolong negotiations to suit his convenience till in the end, without a blow being struck, he marched his army south to London. Masterly was the diplomacy and grasp of detail which, on the eve of announcing the Restoration, dispersed over the country all soldiers who would be inclined to stand by the Parliament, making any serious attempt at a revolt on their part impossible.

One failing his most fervent admirer cannot ignore—a strong leaning to avarice. But his popularity was unbounded, and 'it was his singular fortune to win in succession the affection of three very different populations, those of Dublin, Edinburgh, and London.' In Ireland his men were devoted to him. 'A soldier, tho' sick and without shoes, would strive to go out with honest George Monk.' After the death of Cromwell he was offered the crown, but he refused, 'holding it a greater honour to be an honest subject than a great usurper.'

During the frightful visitation of the Plague, the Earl of Craven, and the Archbishop of Canterbury and Monk, were the only high officials who stayed at their posts, and exposed themselves perpetually to the 'seeds of death.' So great was the public confidence in him, that at the time of the Great Fire, he being then at sea, 'the people did believe and say: "If he had been there, the city had not been burned."' No idol of the mob could ask a more whole-hearted adoration.

The popular feeling is expressed in a rather limping acrostic on his name, of which I quote only the first quarter. It was called 'England's Heroick Champion, or The ever-renowned General George Monck.' The date is about 1659-60.

'Good may'st thou be, as thou are great.
Ever regarded.
Or like Alexander compleat,
Richly rewarded.
Gainst thy virtue none dare stand,
Excluded Members now are
Back return'd by thy hand.
'Many miles didst thou compass,
Only us to free;
Nothing by thee too hard was,
Compared to be.
Keep us in thy protection!
We were all greatly distrest;
Bring thou in all the best.
'Great bonfires then was made,
Expressing joy,
Of us that sorrow did invade,
Refresh our annoy.
Guard us with thy aid, we desire;
Exaltation we all will raise
Unto heaven in thy praise.
'Much good hast thou already done,
Over this land;
Now our hearts thou hast quite won:
Command! Command!
Kindly we will entertain
Those that were excluded,
For they have not intruded.'

In later years, as Duke of Albemarle, he returned to the estate of his forefathers, and rebuilt Potheridge in a very magnificent manner. It has since been pulled down.