A heavy rainstorm caused the Rapidan and Rappahannock to rise so rapidly that Hooker decided, after consulting his officers, to get back while he had the chance to do so. The bridges were covered with pine boughs, and, with the noise of the wheels deadened by the crashing thunder, the wagons and artillery made the passage without discovery. By the following morning, the entire Army of the Potomac was once more across the Rappahannock and marching back to its old camp at Falmouth, and once more the advance against Richmond had ended in woeful disaster. The losses of the Unionists at Chancellorsville were: killed, 1,606; wounded, 9,762; missing, 5,919; total, 17,287. The losses of the Confederates were: killed, 1,665; wounded, 9,081; captured and missing, 2,018; total, 12,764. THE SECOND CONFEDERATE INVASION. After such a frightful Union defeat, it was no wonder that the Confederates again decided to invade the North. Lee was not favorable to the plan, but he must have felt that the prospect of success was better than ever before. He made his preparations with great care, and strengthened his army to 75,000 men, divided into three corps, commanded respectively by Longstreet, Ewell, and A.P. Hill. He had in addition 15,000 cavalry under General J.E.B. ("Jeb") Stuart. The northward march was begun the first week in June. Longstreet and Ewell advanced upon Culpeper, while Hill remained near Fredericksburg, aiming to deceive Hooker as to his intentions. Hooker quickly perceived that most of the rebel army had disappeared from his front, but it was a mystery to him where it had gone. A reconnoissance developed the direction taken by the two missing corps. Unsuspicious of the grand project that was in the mind of the Confederate commander, Hooker moved down the Shenandoah Valley, taking the same course as Lee, but with the Blue Ridge Mountains between them. LEE'S PRELIMINARY MOVEMENTS. Passing through the defiles in this range, Lee dropped down on Milroy at Winchester before he dreamed of danger. Most of his 7,000 men were captured, but Milroy and a few escaped by a hurried flight at night. All doubt now had vanished as to the intentions of Lee; he was aiming for Pennsylvania, at the head of a powerful, well-organized army; Washington and probably Philadelphia were in peril. The only check that could block its way was the Army of the Potomac, and Hooker lost no time in moving. He reached Fairfax Court-House on the night of the 14th, thus placing himself on the flank of Ewell. The Confederates, however, held the mountain passes securely and nothing effective could be done. [Illustration: ROBERT E. LEE. Confederate Commander-in-chief at Gettysburg. (1807-1870).]