On the 29th, I rose early, roused and warned all the men, and had every one posted, watching for the attack. A little after 6.30 a.m. the enemy opened furiously on the fort, with over twenty guns, and also swept the parapets and rained through the embrasures a heavy fire of musketry from the crest of the ridge 80 to 100 yards off. I went about the fort enforcing strict silence, and seeing that the men were kept close against the parapet, ready to rise and fire. So well had I protected the fort with traverses, and also owing to the fog making it quite dusky, no one was hurt by this fire except one cannoneer. In about twenty minutes the cannonade slackened somewhat, and the musketry fire was directed on the northwest bastion; at the same time a heavy column charged on a run from under the ridge upon the salient of bastion (five regiments formed the column-as near as I could judge, "Column by division closed in mass"). The guns were triple-shotted with canister, but only one got a shot at them, as they came up through the sector without fire. They entanglement, the weight of the column carried them promptly over it. They lost many at the entanglement, and in less than two minutes from their appearance, they were in the ditch, attempting to scale the parapet. As they endeavored to surround the fort,the two guns in the bastion poured triple rounds of canister in their faces (not 10 yards from them),and I soon had the flank gun firing through the ditch and across the salient. They climbed the parapet continually, but only to be shot as they gained the top, the men being ordered to fire at none except those on the parapet. I also threw shells with my own hand in the ditch, to explode among them. After a while they began to fall back, but another column coming up, the assault was pushed more savagely than ever, and three of their flags were planted in our parapet. At length they again fell back in great confusion to the ridge from which they charged, leaving the ground strewn with dead and dying and three colors in our possession.

We took over 250 prisoners unhurt, 17 of them commissioned officers (we were not 250 strong in the fort); over 200 dead and wounded lay in the ditch, among them 3 colonels. One-half in the ditch were dead; most of the others were mortally wounded. We also got over 1,000 stand of arms. The prisoners in the ditch represented eleven regiments, and estimated their regiments their regiments at about 400 strong, each.

From what I learned from their officers and from what I saw, I gathered the following plan of assault: Two brigades to watch and fire on our lines, one brigade to assault, and two more to support it. Two brigades came up to the ditch. The party actually engaged in the assault numbered about 4,000 men, not including reserves. Of these they lost from 1,300 to 1,500 killed, wounded, and prisoners; a very large proportion killed, and a large number mortally wounded.

In the fort we lost 13 men, 8 killed and 5 wounded.

General Ferrero was in the little bomb-proof, and I did not see him outside, nor know of his giving an order during the fight. The capture of the fort was to have been at once followed by a general assault on the town, their whole army being in readiness.

SAMUEL N. BENJAMIN,

Lieutenant, Second U. S. Artillery.