topographical features of the country and the positions of the intrenched lines of both armies, and by the 30th of the same month was far advanced. During the progress of the siege this map proved of the greatest importance, and constant reference was made to it.

In closing this part of the report in relation to the labors of the topographical department of the army during the period called for by the major-general commanding, it may be of interest to know that over 1,300 miles of actual surveys were made; that move than 1,200 maps were issued to the army previous to taking up the line of march across the Rapidan, and over 1,600 photograph sketches between that date and the 30th of July.

It would not be just to my assistants to refrain from expressing the appreciation I entertain for the unwavering and cheerful energy at all times displayed by them in the performance of their duties. The amount and accuracy of the work accomplished by them is sufficient evidence of their activity and ability. Exposed night and day to all the hardships and dangers of the campaign, it was under the most trying circumstances that their duties were performed. The usual conveniences afforded persons so employed were necessarily denied to them, but they were ever ready for any emergency and prompt to execute any instructions. The particular attention of the commanding general is called to the extent and difficulty of the labors performed by them. The silent and arduous labors of the engineer, upon which depends to such a great extent the success of a campaign, are too apt to be forgotten and overshadowed by the brilliancy of the noble and brave deeds of other arms of the service.

In this report it will be unnecessary to enter into great detail upon the many various engineering operations of the campaign aside from the one branch of duty already alluded to, particularly as some of them have been elaborately presented in accompanying documents, nor will an accurate description of the country passed over be attempted, as it will no doubt be more vividly pictured by others. The portfolio of maps* which is appended to this paper must for the present exhibit the lines of operations of the army and the localities of the various fields of battle until additional time and more advantageous circumstances permit the perfecting of them. Exact and beautiful drawings of the several points of interest are in course of construction. A brief synopsis will, therefore, be given of the different duties assigned to the several officers apart from those already enumerated in other reports in the order of events as laid down in Special Orders, Numbers 209.

FIRST EPOCH.

The crossing of the Rapidan and the battles of the Wilderness.

On the 3rd of May Lieutenant R. S. Mackenzie was directed to report to General Gregg and accompany the movement of the Second Cavalry Division. He remained with this command, after crossing the Rapidan at Ely's Ford, during the 4th and 5th, and participated in a skirmish with the enemy's cavalry at Todd's Tavern. On the 6th he returned to the Engineer Battalion, and the following day reported to the chief engineer for temporary duty at headquarters. Lieutenant C. W. Howell was also detailed on the 3rd to go with the Third

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*Such of the maps as may be found will appear in Atlas.

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