to gain possession of which the rebel authorities directed their efforts, as well as to divert our armies from the attack on Richmond. At Antietam and South Mountain they had been defeated and driven back into the Valley of the Shenandoah. Again they made a powerful effort and were defeated at Gettysburg and driven across the Potomac and up the valley. In July, 1864, after the lieutenant-general had forced the rebel armies concentrated under Lee from Todd's Tavern, through Spotsylvania and Cold Harbor, into Richmond and Petersburg, they made another effort to divert the lieutenant-general by detaching Early on another expedition down the Valley of the Shenandoah and across the Potomac, threatening Baltimore by moving on the Monocacy, where a small body of our troops were repulsed, thus jeopardizing both Baltimore and Washington. The attention of the lieutenant-general was given to these efforts of his adversary to divert him from his main object-the defeat and capture of Lee's army-and, while withdrawing part of the garrison to re-enforce the armies operating against Richmond, he held the command of his rear and Washington by being enabled to transport from before Petersburg as large a force as Lee could detach to operate in the valley and on Washington. Many thousands of wounded and sick occupied the hospitals in Washington, and the troops fit for duty did not suffice to man the armaments of the forts around the city. The engineers had previously constructed a system of detached redoubts and forts around the city on a circuit of upward of thirty-five miles. Early, after his success at Monocacy, moved directly upon the defenses of Washington between the Potomac and the Eastern Branch. (See plan Numbers 1.) Colonel Alexander of the Corps of Engineers, was the only officer of the corps Woodruff and Major Kurtz, of the Corps of Engineers, and assistants of the Chief Engineer, were first ordered to these defenses. Subsequently all the officers on the sea-coast, north and east of this city, were detached from their labors of constructing sea-coast batteries (then threatened by rebel iron- clads building in Europe, as another effort to divert our armies in the field), and were ordered to the defenses of Baltimore and Washington-Major Prime, Captain Baltimore, and Colonel Macomb, Major Blunt, Major Casey, and Captain Tardy to the aid of Colonel Alexander at Washington. The rebel blow was aimed at Washington. The wise foresight of the Secretary of War had caused all the employes of the several bureaus of his Department to be organized and drilled as infantry troops. The necessity for the withdrawal of the Sixth Army Corps from Petersburg and of the Nineteenth from New Orleans had also been foreseen, and orders sent to them to proceed to this city to meet the blow that was threatened. The Veteran Reserves and convalescents from the hospitals were also ordered to garrison the defenses. Requisitions were made upon the Governors of States to furnish troops, but with little success. The Sixth and Nineteenth Corps arrived at the most opportune moment. Early directed his efforts upon Fort Stevens, but finding the garrison re-enforced, and even moving out of the defenses to meet him, he suddenly retreated across the Potomac and up the Valley of the Shenandoah. The engineers were then ordered to their former stations on the sea-board.

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*Plate LXXXIX, Map 1, of the Atlas.

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