Before proceeding further he calls attention to the topographical department of the Army of the Potomac.

Owing to the limited degree of information which could be obtained, either from generally being averse and in most cases unable from ignorance to impart it, even in relation to the particular localities in which they lived-his assistants had a laborious although an interesting duty. They have not only been constantly engaged in following up every movement, and in most cases acting as guides to the different columns of troops, thereby obtaining a most reliable knowledge of the country by actual experience, but have been compelled to anticipate the country by actual experience, but have been compelled to anticipate the geographical wants of a large army ever in motion by constant and careful researches.

In order to be able to furnish the necessary date upon which to base the different military combinations, and thereby being made responsible to a great extent for the information upon which the commanding general was able to hypothecate a reasonable degree of success in the execution of his plans, the department had necessarily to be ever active and always exact.

The Engineer Bureau has been furnished from time to time with the many maps supplied the officers of armies operating against Richmond and Petersburg, including those of the campaigns from the Rapidan to the Appomattox; that of the carefully surveyed plan of the lines occupied during the siege of Petersburg; the several sheets representing the country adjacent to the latter city, and also about Richmond, comprising the several lines of the enemy for the defense of the capital; and also copies of those prepared in anticipation, and upon which were based the movements which terminated so successfully and gloriously the last grand campaign of April, 1865.

On the 27th of March certain movements of the several corps of the Army of the Potomac were ordered to commence at an early hour of the 29th. On the 28th the instructions of the previous day were somewhat modified, but at the appointed time the several columns were in motion.

A pontoon train accompanied the Fifth Corps to enable it to cross Hatcher's Run, and subsequently remained there for the passage of the general trains. The Second Corps, which had been replaced by a portion of the Twenty-fourth along the intrenched line heretofore occupied by it, crossed by the bridge on the Vaughan road. The cavalry passed over by a bridge still farther down, at Malone's Crossing, and moved toward Dinwiddie Court-House.

In gaining their position but little opposition was encountered; one division of the Fifth had a spirited engagement on the Quaker road, and handsomely repulsed the enemy.

On the 30th the Second and Fifth Corps advanced their lines to beyond the junction of the Quaker and Boydton plank roads, driving the enemy into his main works; the two lines were within easy artillery range; the right of the Second now rested on Hatcher's Run, near the Crow house. A division of the Twenty- fourth Corps crossed the run and connected the right of the Second with the tete-de-pont on the Vaughan road; both lines were intrenched.

During the night previous and throughout the whole of this day the rain poured down in torrents. The roads had become impassable for wagons and artillery, and the engineer troops were engaged in corduroying them and in rebuilding bridges over Hatcher;s and Gravelly Runs.