But Lee, though cornered, was not yet caught. He had to think and act quickly but though he had only 45,000 men and Hooker had 70,000 on the spot, his idea was not to escape but to attack. A close examination of the opposing lines in front and at the Federal left disclosed no weakness, but the right beyond Chancellorsville looked more hopeful. Then a brilliant idea suddenly occurred to his mind. The Union commander was evidently awaiting or meditating a direct attack and had no fear except that his prey might escape him. Might it not be possible to keep him busily occupied in front, while a force stole behind his right wing and caught it between two fires? This was precisely what Hooker had been endeavoring to do to him, but Lee was well aware that what was safe for a large army might be ruinous for a small one and that his proposed maneuver would require him to divide his small army into two smaller parts, both of which would be annihilated if the move was discovered. But capture or destruction stared him in the face any way, so, learning from a certain Colonel Welford that a road used by him in former years for transporting materials to a local furnace could be utilized to swing a considerable force behind Hooker's right, he determined to take the desperate chance. The necessary orders were accordingly issued during the night of May 1, 1863, and by daylight the next morning Jackson started off on the back trail with about 30,000 men, leaving Lee with only 15,000 to face Hooker's overwhelming array. The success of the whole enterprise depended upon the secrecy and speed with which it was conducted, but Jackson had already proved his ability in such work and his men set off at a brisk pace well screened by vigilant cavalry. It was not possible, however, wholly to conceal the march, and not long after it began several quite definite reports of its progress reached Hooker. But though he duly warned his Corps Commanders to be on their guard against a flank movement, he himself evidently interpreted it as the beginning of a retreat. Indeed, by four o'clock in the afternoon of May 2nd he became convinced that his victims were striving to escape, for he advised Sedgwick, "We know that the enemy is fleeing, trying to save his trains." But even as he dispatched this message Jackson was behind at the Union right and his men were forming in line of battle under cover of a heavy curtain of woods.