On the 22d the headquarters of Lee were at Beverly, ten miles from Winchester, with which Lee kept up communication through A.P. Hill's corps, which was between Culpeper and Front Royal. Ewell, without hesitation, forded the Potomac into Maryland, while his cavalry pushed on into Pennsylvania. By this time the government was so alarmed that President Lincoln, on the 15th of June, called by proclamation on the governors of Ohio, Pennsylvania, Maryland, and West Virginia to furnish 100,000 militia for the protection of those States. Pennsylvania, the one in greatest danger, was so laggard that she asked New Jersey to come to her help, and that little State gallantly did so. GENERAL MEADE APPOINTED TO THE COMMAND OF THE ARMY OF THE POTOMAC. Hooker deserved credit for appreciating his own unfitness for the command of the army that was again to fight Lee. He crossed the Potomac June 26th, making a movement which threatened Lee's communications, and resigned the next day. At Frederick, on the 28th, he published an order to the effect that the army had been placed in charge of Major-General George G. Meade. This was an excellent appointment. Although Meade was born, in 1815, in Cadiz, Spain, he was an American, because his father was the United States naval agent at the time. Meade was graduated from West Point in 1835, and won distinction in the war with the Seminoles and with Mexico. The appointment was a surprise to him, but it pleased everybody, and he modestly took hold, resolved to do the best he could. MOVEMENTS OF GENERAL MEADE. He adhered to the general plan of Hooker. His army numbered about 100,000, and no braver men lived anywhere. Nearly all of Lee's troops were north of the Potomac, partly in Maryland and partly in Pennsylvania. On the 27th of June the whole army was at Chambersburg, Pennsylvania; but Lee was greatly hampered by the absence of Stuart and his cavalry. That dashing officer was very fond of making raids, and, giving a wider meaning to the permission of Lee than that general intended, he was off on another of his bold ventures, with no certainty as to when he would return. It was upon him that Lee was obliged to depend for news of the Union army. Receiving none, he was on the point of advancing against Harrisburg, the capital of Pennsylvania, when he paused upon receiving the first reliable news of the Army of the Potomac. Meade had pushed his advance beyond Middleton, where his left was lying when he took command of the army at Frederick. This action of the Union commander looked as if he intended to cross the mountains and attack the Confederate rear. Ewell's corps was at York and Carlisle, but still there was no knowledge whatever of the whereabouts of Stuart.