Soon after the troops fell back, Gen. Pope was relieved, at his own request, and Gen. McClellan re-instated as Major General commanding. He immediately commenced the labor of re-organizing the army. The lull which followed, and absence of the enemy from our immediate front, boded no good. The news, therefore, which soon reached Washington, that the rebels had made their appearance near Edward’s Ferry, was not wholly unexpected. Friday night, Sept. 5th, they crossed the Potomac and occupied Frederick City with a heavy force, destroying the Baltimore and Ohio Railroad for several miles, and cutting off communication with Harper’s Ferry and Martinsburg, where considerable bodies of our troops were stationed. Gen. Lee’s plan, he afterwards stated, in crossing the river, was to threaten Baltimore, Washington and Harrisburg at the same time, thereby diverting the attention of our authorities while he encircled and captured the above forces. Gen. McClellan immediately pushed forward to meet him.

SUGAR-LOAF MOUNTAIN, MARYLAND.

Saturday evening, Sept. 6th, Franklin’s Corps crossed the Long Bridge, followed by Sumner’s and Hooker’s (late McDowell’s), and proceeded up the Maryland side of the river. All night long the solid, heavy tramp of troops could be heard through the streets of the capital.

The Thirty-third passed up Pennsylvania Avenue about 7 o’clock, and marching until 2 o’clock Sunday morning, halted at Tanlytown. The march was resumed at 5 o’clock P. M., and continued for six miles.

Monday, Sept. 8th, marched through Rockville, halting one mile west of the place. Many of the knapsacks were left here, and afterwards sent back to Washington. Resuming the march, bivouacked four miles east of Darnestown.

Tuesday, Sept. 9th, moved at 9 o’clock A. M., and encamped near Seneca Creek. The weather was very warm and roads dusty, but, relieved of their knapsacks and other effects, the soldiers suffered comparatively little.