but also in the entire absence of reliable guides t act as such to the different columns, either as they moved along their respective routes of march or while maneuvering for favorable positions previous to an attack.

Major John E. Weiss, commissioned by the Governor of the State of Kentucky, acted as my principal assistant, and Captain W. H. Paine, additional aide-de-camp, was also attached to the Engineer Department as an assistant. In addition to these there were seven civil assistants, besides several men detailed from the ranks to act in various capacities. The names of the former are Mr. Ferd. Theilkuhl, W. Burchard, Franz Schumann, E. Myers, L. C. Oswell, George L. Crane, and John H. Mullen. Some of them had been connected for a long time with the Army of the Potomac, and had gained great experience in making rapid reconnaissances and surveys, and in executing topographical sketches. Their duties commenced immediately after crossing the Rapidan, the surveys being connected with those previously extended to that river, and progressed without interruption or rest until the army arrived in front of Petersburg; nor did they then cease, but have continued along without any interruption to the present time. Each and every road within the lines of the army was examined and surveyed, and their researches were pushed as far to the front and on the flanks as it was compatible with safety to go without incurring any unnecessary risk of capture. The notes were immediately plotted and the maps compiled and at once photographed for the use of the officers of the command. In addiction to the general topographical features of the country being represented, the respective lines of battle taken up at different times and at various localities were located. These were executed under the fire of the sharpshooters, and as well as the constant daily fighting would permit. As rapidly as any new information could be procured new editions of the maps would be prepared and photographed, and widely distributed. In this way, from the crossing of the Rapidan on the 4th of May to the explosion of the mine of the 30th of July, several editions of each of eleven separate sheets were arranged and issued, comprising surveys which cover an area of 737 square miles. In addition to the surveys already referred to there were several others not embraced on the photograph sketches, comprising one from the Germanna Ford to Petersburg, taken by the headquarters train of wagons along which the measurements were made by an odometer, a distance of over 179 miles, and also those made in company with the cavalry expeditions under Major-General Sheridan, the first from Chancellorsville to Haxall's Landing on the James River, and the last from Cold Harbor to Trevilian Station on the Virginia Central road and back to the White House, in the aggregate a distance of 310 miles. These actual surveys have since been compiled with information obtained from maps captured from the enemy, and the original series of campaign sheets corrected by this additional matter. Six sheets have thus been improved upon, including those styled Culpeper, Chancellorsville, Fredericksburg, Hanover, Richmond, and Petersburg, the originals of the first five of which are in the hands of the engraver, having been previously photographed for any immediate use.

On the 9th of July, the date of the order directing that "the operations of this army against the intrenched position of the enemy defending Petersburg will be by regular approaches," a trigonometrical survey of the environs of that city was commenced, showing the