[352] _Memorandum on the Defence of Portugal_, of March 7. It is the survey of documents such as these that enables us to appreciate Wellesley at his best. He had gauged perfectly well the situation and difficulties of the French. He saw exactly how much was in his own power. The whole history of the Peninsular War for the next two years is foreseen in his prophetic statement, that with 30,000 British troops and the Portuguese levies he would guarantee to hold his own against any force of less than 100,000 French, and that he did not think that the enemy would find it easy to collect an army of that size to send against him. This is precisely what he accomplished: for the first fifteen months after his arrival he held with ease that frontier which Moore had described as ‘indefensible against a superior force.’ When at last Napoleon, free from all other continental troubles, launched against him an army under Masséna, which almost reached the figure[353] that he had described as irresistible in 1809, he showed in 1810-11 that he had built up resources for himself which enabled him to beat off even that number of enemies. Though four-fifths of Spain had been subdued, he held his own, because he had grasped the fundamental truth that (to use his own words) ‘the more ground the French hold down, the weaker will they be at any given point.’ In short, he had fathomed the great secret, that Napoleon’s military power--vast as it was--had its limits: that the Emperor could not send to Spain a force sufficient to hold down every province of a thoroughly disaffected country, and also to provide (over and above the garrisons) a field army large enough to beat the Anglo-Portuguese and capture Lisbon. If the French dispersed their divisions, and kept down the vast tracts of conquered territory, they had no force left with which to take the offensive against Portugal: if they massed their armies, they had to give up broad regions, which immediately relapsed into insurrection and required to be subdued again. This was as true in the beginning of the war as in the end. In 1809 the army that forced Wellesley to retreat after Talavera was only produced by evacuating the whole province of Galicia, which passed back into the hands of the insurgents. In 1812, in a similar way, the overpowering force which beat him back from Burgos, had been gathered only by surrendering to the Spanish Government the whole of the four kingdoms of Andalusia. On the other hand, during the long periods when the enemy had dispersed himself, and was garrisoning the whole south and centre of Spain, e.g. for the first six months of 1810, and for the last six months of 1811, Wellesley held his own on the Portuguese frontier in complete confidence, assured that no sufficient force could be brought up against him, till the enemy either procured new troops from France or gave up some great section of the regions which he was holding down. A detailed insight into the future is impossible to