It is a remarkable circumstance that the officers who had studied tactics in what were considered as the best schools, under Vere in the Netherlands, and under Gustavus Adolphus in Germany, displayed far less skill than those commanders who had been bred to peaceful employments, and who never saw even a skirmish till the civil war broke out. An unlearned person might hence be inclined to suspect that the military art is no very profound mystery, that its principles are the principles of plain good sense, and that a quick eye, a cool head, and a stout heart, will do more to make a general than all the diagrams of Jomini. This, however, is certain, that Hampden showed himself a far better officer than Essex, and Cromwell than Leslie. The military errors of Essex were probably in some degree produced by political timidity. He was honestly, but not warmly, attached to the cause of the Parliament; and next to a great defeat he dreaded a great victory. Hampden, on the other hand, was for vigorous and decisive measures. When he drew the sword, as Clarendon has well said, he threw away the scabbard. He had shown that he knew better than any public man of his time how to value and how to practise moderation. But he knew that the essence of war is violence, and that moderation in war is imbecility. On several occasions, particularly during the operations in the neighbourhood of Brentford, he remonstrated earnestly with Essex. Wherever he commanded separately, the boldness and rapidity of his movements presented a striking contrast to the sluggishness of his superior. In the Parliament he possessed boundless influence. His employments towards the close of 1642 have been described by Denham in some lines which, though intended to be sarcastic, convey in truth the highest eulogy. Hampden is described in this satire as perpetually passing and repassing between the military station at Windsor and the House of Commons at Westminster, as overawing the general, and as giving law to that Parliament which knew no other law. It was at this time that he organized that celebrated association of counties to which his party was principally indebted for its victory over the King. In the early part of 1643, the shires lying in the neighbourhood of London, which were devoted to the cause of the Parliament, were incessantly annoyed by Rupert and his cavalry. Essex had extended his lines so far that almost every point was vulnerable. The young prince, who, though not a great general, was an active and enterprising partisan, frequently surprised posts, burned villages, swept away cattle, and was again at Oxford before a force sufficient to encounter him could be assembled.