ducing every castle in his way; which must be a work of much time and difficulty, nor would be able to afford men to block them up, and secure his retreat: which way of arguing may be good enough to a prince of an undisputed title, and entirely in the hearts of his subjects: but, numerous castles are ill defenders of an usurpation, being the common retreat of malecontents, where they can fly with security, and discover their affections as they please: by which means, the enemy, although beaten in the field, may still preserve his footing in the bowels of a country; may wait supplies from abroad, and prolong a war for many years: nor, while he is master of any castles, can he ever be at mercy by any sudden misfortune; but may be always in a condition of demanding terms for himself. These, and many other effects of so pernicious a counsel, the king found through the whole course of his reign; which was entirely spent in sieges, revolts, surprises, and surrenders, with very few battles, but no decisive action: a period of much misery and confusion, which affords little that is memorable for events, or useful for the instruction of posterity.
1136. The first considerable enemy that appeared against him was David king of Scots; who having taken the oath of fealty to Maude and her issue, being farther engaged by the ties of blood, and stirred up through the persuasions of several English nobles, began to take up arms in her cause; and invading the northern parts, took Carlisle and Newcastle; but, upon the king's speedy approach with his forces, a peace was presently made, and the towns restored. However, the Scottish prince would, by no means, renounce his fidelity to the empress, by
