can accomplish such important duties, also bear testimony to the zeal, energy, and ability displayed by both officers and men, and to the important services rendered by this arm of the service, not only during the weary marches of a long and trying campaign, but also in the preparation and execution of the more tedious operations of the siege.

In justice to those attached to the engineer party at the headquarters of the army, both officers and civil assistants, and to show the nature and extent of the labors performed by them, I beg leave to submit a brief synopsis of the duties connected with the topographical department, the special charge of which had been for several months previous to and during the campaign under my immediate care and direction. In addition I would wish to state the different occasions on which the several officers of engineers on duty with the army were detailed from their respective command, and under personal instructions from the chief engineer performed valuable professional labors. As that officer is not here to attend to what would no doubt prove a pleasing and interesting duty to him, and one which he is so well able to perform, having been compelled to leave the field in consequence of partial sunstroke received the very last day of the period covered by this report, it becomes necessary for me to undertake the preparation of a general summary of the operations of the department.

During the winter months previous to the opening of the spring campaign, from the 10th of December to the 1st of May, a large umber of original drawings of campaign maps were prepared under my direction (twenty-nine sheets in all), comprising the country from Gettysburg south to Petersburg, and from the Chesapeake Bay as far west as Lexington, in readiness for the movement of the army in whatever direction it might march after breaking up the winter camps near the Rappahannock River and along the Orange and Alexandria Railroad. The scale adopted was 1 mile to the inch, being the most convenient by which to make any addition or corrections ont eh different sheets, the distances being more readily measured without instruments. These maps were compiled from actual surveys and reconnaissances made by the officers and assistants of the engineer department on duty with the army at various times, both during the previous movements of the troops in other portions of the country, and throughout the more recent operations between the Rapidan and Bull Run, and by such additional matter as could be obtained from the best authorities, both State and country. In searching for the latter, the series of maps prepared by the Bureau of Topographical Engineers of the War Department proved of the utmost utility. The copies furnished by the U. S. Coast Survey of the maps of the several rivers likely to be encountered, such as the Rappahannock, the York, and the James, and the chart of the Chesapeake Bay, were also invaluable. When prepared, the sheets were successively forwarded to the Bureau of Engineers at Washington, with the request to have them either photographed, lithographed, or engraved. By the time the army was ready to move, they were distributed for general use, each of them covering an area of 875 square miles, and subdivided into 5 miles square for the sake of easy reference. In addition to these detailed maps, the following general ones were distributed among the officers of the command: Central Virginia, compiled in the Bureau of Topographical Engineers of the War Department, scale 1/360 000-inch, and part of the map of the Military