A few days afterwards nearly the whole of his old regiment had enlisted with Fairfax, while he and Warren were sent prisoners to Hull. But for such a man Hull was not safe enough. It had but recently been relieved, and was not out of danger so long as Lord Newcastle was at York. Fairfax and the other officers who had fought by Monk's side in the Low Countries knew well the value of his services, and impressed upon the Parliament that he was "a man worth the making," and not without effect. He was ordered up to London with Warren, and on July 8th brought to the bar of the House. There the two unfortunate officers were charged with high treason and committed to the Tower. No sooner were they there than Lord Lisle set about justifying his boasts to the Council. He was still doing his best to get appointed Lord Lieutenant of Ireland, and there could be no better testimonial to his fitness than that he could command the services of the officers in the Tower. Of Monk there was every hope, for he alone had refused to bind himself not to serve the Parliament, nor were the most enticing offers wanting to tempt him.
Already the New Model Army was in contemplation. Men of all parties saw that nothing decisive would ever be done except by adopting the methods which Monk had urged on the King. A compact mobile field-force, complete and organised in every detail on the Low Country system, must replace the unmanageable mobilised militia with which the war had hitherto been aimlessly dragged on. Cromwell had now definitely come to the front and thrown himself into the task. Except possibly Sir Jacob Astley, who was at Oxford with Charles, there was no one in the kingdom more fitted for the all-important work than Monk. Cromwell, who knew how to choose a man, must have been perfectly aware of his qualifications, even if he had not been as intimate as he was with Lord Lisle. Nor was it from Cromwell alone that the prisoner was tempted. Though all were agreed the weapon must be forged, they were by no means at one as to the hands in which it was to be placed. Independents and Presbyterians were manœuvring for the control. In spite of standing orders members were so constantly visiting the prisoners that the House had strictly to forbid the practice without special leave. The same day a leading Presbyterian was granted permission, and towards the end of October Monk's case was specially referred to the committee of examinations.
But they all mistook their man. He still held the King's commission. The war for which he had engaged was still raging, and the most brilliant offers that could be made him he only regarded as insults. Pressure was even brought to bear, it is said, by a more rigorous confinement, but it was useless, and he indignantly refused his liberty except by a regular cartel.
Days and weeks went by and no exchange came. Although, as he had refused to desert in Ireland, he was not affected by the order which forbade the exchange of the other Irish officers upon any terms, Parliament had no intention of allowing so valuable an officer to get back to the royal camp. In vain Daniel O'Neill urged the King to procure his release for service in Ireland. Charles seems to have done his best. Clarendon says that many attempts were made to exchange him; that one was we know. Care, however, seems to have been taken by his would-be employers not only that these attempts should be unsuccessful, but that Monk should not even hear of them. The wretched colonel thought himself forgotten. His money was gone, and a penniless prisoner in those days was the most miserable of men. Of his annuity fifty pounds was all he had had, and on November 6th, but four months after his committal, he sat down to write an urgent appeal to his brother for another fifty. The letter concludes with a pathetic cry for his release: "I shall entreat you," he says, "to be mindful of me concerning my exchange, for I doubt all my friends have forgotten me. I earnestly entreat you, therefore, if it lies in your power, to remember me concerning my liberty; and so in haste, I rest, your faithful brother, George Monk."
In haste and in the Tower! But any excuse was good enough with the taciturn soldier if it saved words. And he might have saved them all. Exchange and remittance were alike out of the question with his hard-pressed brother, and as the weary months went by he thought himself indeed deserted. Once out of the very depth of his poverty Charles sent him a hundred pounds—an extraordinary mark of esteem as things went at Oxford then. But that was all. Bitterly he felt the seeming ingratitude, but in spite of all with obstinate loyalty he refused to desert his colours, and sat himself down to forget in the pursuit of literature the fancied wrongs under which he smarted.
Like many other active-minded men before and since, having absolutely nothing to do he determined to write a book. He had before him the example of Lord Vere and his brother-in-arms, Hexham, the literary quartermaster of his old Low Country regiment, and most worthily he followed in their steps. The book is full of vigorous and pithy aphorisms which flash on us the condensed opinions of a man who spoke little and thought much. We can hear, as we read it, the few well-digested words, rugged, blunt, and direct, with which he compelled the attention of councils of war and won the respect and admiration of his men. Its subdued enthusiasm tells us of a genuine soldier reverently devoted to his profession, and looking mournfully from the place apart, where his almost aggressive patriotism had placed him, at the distractions with which his beloved country was torn. It gives us as clearly as though we saw him face to face the key of the character that has been as much misunderstood and abused as any in history. He was an English citizen first, a soldier next, and a politician not at all. Of the real meaning of the strife he was incapable of grasping any conception. For him it was all a mere question of the interior, and in his eyes no question of the interior, not even religion itself, was worth a civil war, or the sacrifice of England's military renown.
He called his work Observations upon Military and Political Affairs. The military part is admirable, and shows us the consummate soldier he was. It strikes one of the first notes of modern military science, and takes for its dominant theme the comparatively small part which actual fighting plays in the duties of a general and the success of a campaign. The political observations are more crude but equally characteristic. With the exception of some sagacious remarks on governing a conquered country, they are confined to the methods of preventing civil war. After recommending a strong centralised government, technical education, and uniformity of religion, if it can be obtained without danger, he enunciates those principles which caused him to take the final step at the great crisis of his life. Still under the influence of his Devonshire training he strongly insists on State colonisation as a means whereby sources of weakness may be turned into strength. "But the principal and able remedy," he says, "against civil war is to entertain a foreign war. This chaseth away idleness, setteth all on work, and particularly this giveth satisfaction to ambitious and stirring spirits; it banisheth luxury, maketh your people warlike, and maintaineth you in such reputation amongst your neighbours, that you are the arbitrators of their differences." And it is from this point of view that he expresses his only opinion on the great question that was coming. "A sovereign prince," he lays down, "is more capable to make great and ready conquests than a commonwealth, and especially if he goeth in person into the field."
When the manuscript was complete he gave it to Lord Lisle to take care of, and thus we may be sure that it was from Monk's pen that Cromwell, to whom Lisle would not have omitted to show his treasure, learnt something at least of his knowledge of war.
But literature was not his only consolation. There was another more to his taste and less to his credit. For there used to come to the Tower one Ann Ratsford, the wife of a perfumer who lived at the sign of the Three Spanish Gypsies in the Exchange. By trade she was a milliner, and in that capacity used to look after Monk's linen. She was neither pretty nor well bred; she had a sharp tongue and manners that were not refined. But the colonel was soft-hearted, and she was very kind; the colonel was so handsome and had such a soldierly air, and then all his friends had forgotten him and the perfumer was detestable. So the gloomy walls of the Tower were brightened with an unholy idyl, and thus began the intrigue which was to make a duchess of plain Nan Clarges, the farrier's daughter of the Savoy.