APRIL 27-29, 1864. - Expedition from Williamsburg and skirmish at Twelve-Mile Ordinary, Va.

Report of Colonel Benjamin F. Onderdonk, First New York Mounted Rifles.

HEADQUARTERS FIRST MOUNTED RIFLES,
Near Williamsburg, Va., April 29, 1864.

COLONEL: I have the honor to report, pursuant to order of the 27th instant, I marched at an early hour. Nothing of importance occurred until we reached the long woods beyond Twelve-Mile Ordinary, where we were fired on by scouts, one of whom (Davis) we captured. The next picket, near Slatersville, we charged to New Kent, capturing 3. The most reliable information I could gain was that there is no force at Tunstall's Station, on the Pamunkey. I could get no information. At Bottom's Bridge are 2,000 infantry and artillery, with Holcombe's battalion of cavalry. Nine field guns are constantly on duty. All the public fords on the river above Ford's Bridge are blockaded and heavily guarded. a large force is stationed at a central point, from which re-enforcements can be thrown to any point above New Bridge in half an hour. Fifteen thousand can be brought to the defense of Bottom's Bridge in that time. Ford's Bridge Ford, three days since, was only defended by a small picket. There is also a picket at Charles City Court-House. The camp of this force performing this duty (supposed to be the Forty-second Battalion) is 6 miles from the court-house, toward Richmond. At the latter place the people are in great excitement. The enemy are strengthening fortifications, and troops are constantly arriving from the direction of Charleston. I believe the Charles City Court-House road is the least defended. There is no force this side of Bottom's Bridge except one troops of the Holcombe Cavalry, at Cedar Hill, 2 miles beyond New Kent Court-House, to picket the roads, but they retreat at the shortest notice. We reached New Kent Court-House at 12. 45; rested and hour and half; returned to Barhamsville, where we halted two hours to feed and supper. Finding the horses very fresh, I decided to return.

In the long woods, 1 mile beyond Twelve-Mile Ordinary, we were attacked at 9 o'clock by an ambuscade (supposed to be the Peninsula Scouts); they had scattered torpedoes or shells, with friction fuses, in the road, six of which exploded in my column, the fire of the fuses making a strong light, of which the enemy took advantage to fire on the men. I wheeled into line, and gave the enemy a volley, which caused them to leave, but they returned again and kept up a continuous fusilade on my entire column as it passed. I did not deem it advisable to follow them into the woods, as I had reason to suppose their internal machines might do me more injury than the random fire. Although the shells exploded in the midst of the horses and men, strange to say but one man and two horses were slightly wounded with pieces of shell. My men behaved as coolly as on parade, although the uncommon style of warfare was sufficient to destroy the equanimity of the best troops. I should judge the machines to be about 20-pounder shells; they seemed to be charged with canister. Major Hamilton deserves particular notice for his coolness and gallantry through the entire trip. My thanks are due Major James N. Wheelan for volunteering to lead a small party around from Barhamsville to cut off the picket at New Kent Court-House,