At about midnight, however, I was aroused by Captain Moses, of General Heintzelman's staff, who informed me that the general was apprehensive that the enemy were evacuating, from the fact of the constant cannonading, and that a heavy fire was also raging in Yorktown. I immediately ascended and saw that the fire was confined to one building or vessel near the wharf, and therefore I did not consider it a sufficient indication that they were evacuating, for if destruction of property was intended, they would burn their barracks, tents, wharves, store- houses, &c., I therefore considered the fire to be accidental.

I did not sleep any more, however, that night, and got the balloon ready for another ascension, which I made before daylight; but, as formerly, at this time in the morning I could see no camp-fires. As soon as it became a little lighter I discovered that the enemy had gone. This I immediately communicated to General Heintzelman, who on learning it ascended with me, satisfied himself of the fact, and reported it by telegraph to General McClellan, sending the message down from the balloon without descending. We then remained up and saw our troops advance toward the empty works, throwing out their skirmishers, and feeling their way as if expecting to meet an enemy. Of course we had no means of communicating to let our advance guard know where the enemy were, which we could see, as their rear guard was not more than one mile from Yorktown.

From the above facts it is fair to presume that the first reliable information given of the evacuation of Yorktown was that transmitted from the balloon to General McClellan by General Heintzelman and myself. Further proof of this, if necessary, will be found in General Heintzelman's report of the battle of Williamsburg, which I regret I have not at hand to quote from.*

I would also refer to the pamphlet written by Prince de Joinville, where in speaking of the evacuation of Yorktown and in other places he alludes to the ascensions of the balloon as an everyday occurrence in the Army of the Potomac for reconnaissances, and of their being frequently fired at by the enemy.

At about 7 o"clock the balloon was taken into Yorktown and observations made of the river for thirty miles. From the reports made that a number of vessels were in sight, our gun-boats were enabled to capture some and cause the destruction of many more.

To show how suddenly the enemy withdrew from Yorktown, I insert the following report to General Keyes, made verbally at the time and subsequently in writing:

ROPER'S MEETING-HOUSE, May 11, 1862.

Brigadier General E. D. KEYES,

Commanding Fourth Corps, Army of the Potomac:

GENERAL: In accordance with your request that I should give you a statement of the results of my observations from the balloon stationed at General Smith's division, near Warwick Court- House, on Saturday, May 3, I give the following:

I ascended at noon, and remained at an elevation of nearly a thousand feet for one hour. Could see the rebel line of works and camps from York to James Rivers. At a point which I took to be Lee's Mill there seemed to be a large camp and earth-works as well as many others to the right and left. In several places there seemed to be gangs of men apparently throwing up earth- works. In addition to their barracks, many tents were visible, and, in fact, signs of evacuation were not visible. I reported the result of my observation to General McClellan on the same evening, and also to you at Brigadier-General Smith's headquarters at about 4 p.m. the 3rd instant. On the following morning I ascended at a point

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* But see Series I, Vol. XI, Part I, p.456.

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