This failure of Howe to coöperate with Burgoyne was no doubt the most fatal military blunder made by the British in the whole course of the war. The failure was of course unintentional on Howe's part. He meant to extend sufficient support to Burgoyne, but the trouble was that he attempted too much. He had another plan in his mind at the same time, and between the two he ended by accomplishing nothing. While he kept one eye on Albany, he kept the other on Philadelphia. He had not relished being driven back across New Jersey by Washington, and the hope of defeating that general in battle, and then pushing on to the "rebel capital" strongly tempted him. In such thoughts he was encouraged by the advice of the captive General Lee. That unscrupulous busybody felt himself in great danger, for he knew that the British regarded him in the light of a deserter from their army. While his fate was in suspense, he informed the brothers Howe that he had abandoned the American cause, and he offered them his advice and counsel for the summer campaign. This villainy of Lee's was not known till eighty years afterward, when a paper of his was discovered that revealed it in all its blackness. The Howes were sure to pay some heed to Lee's opinions, because he was supposed to have acquired a thorough knowledge of American affairs. He advised them to begin by taking Philadelphia, and supported this plan by plausible arguments. Sir William Howe seems to have thought that he could accomplish this early in the summer, and then have his hands free for whatever might be needed on the Hudson river. Accordingly on the 12th of June he started to cross the state of New Jersey with 18,000 men. [Sidenote: Washington's masterly campaign in New Jersey, June, 1777.] But Sir William had reckoned without his host. In a campaign of eighteen days, Washington, with only 8000 men, completely blocked the way for him, and made him give up the game. The popular histories do not have much to say about these eighteen days, because they were not marked by battles. Washington won by his marvellous skill in choosing positions where Howe could not attack him with any chance of success. Howe understood this and did not attack. He could not entice Washington into fighting at a disadvantage, and he could not march on and leave such an enemy behind without sacrificing his own communications. Accordingly on June 30 he gave up his plan and retreated to Staten Island. If there ever was a general who understood the useful art of wasting his adversary's time, Washington was that general.