On the morning of October 19th, we started out, Kilpatrick's Cavalry in advance, in search of the rebs and found them in full retreat, _via_ the Orange and Alexandria Railroad, Warrenton and Leesburg pike, and Thoroughfare Gap. We arrived near Gainesville, where, some months previous, we had fought our first battle. Here we halted a few moments, to mourn over the long mound of earth, which but partly covered the remains of our dead, who on this very ground with our brigade and Stewart's Battery ("B" of the 4th Regulars) had fought the whole of Stonewall Jackson's division for four hours, repeatedly repulsing every attack and holding our ground until, finally, Longstreet's column coming up in our rear, our position became too critical. With Jackson's Division between us and Washington, and Longstreet in our rear, discretion became the better part of valor and we were obliged to retreat, leaving our dead on the field, where this mound now made shift to cover them. History relates that Fitz John Porter had been ordered to check and repulse Longstreet at 4 P.M., and failing to do so was afterwards court martialed, but this is a digression and I must proceed with my story. Resuming our march south, we arrived at the Manassas Gap Railroad, which we crossed, pursuing our course until we came to a little place called Haymarket, where our division was halted in the fields and a detail sent out for picket duty. Forty of this detail were from my regiment, and I was put in command of the quota furnished from the brigade. We advanced about one mile further south and then west, leaving the roads to be picketed by details furnished from the other brigades of the division. Hardly had I established my line, and chosen a place for the support to bivouac, before the enemy slipped in at a place called Buckley's Mills, between the picket and the cavalry in our front, and after a short and sharp engagement they forced Kilpatrick's Cavalry to leave the pike and flee to the south-east, in order to pass around the enemy's flank and return to our lines. The corps was compelled to fall back about three miles in order to get north of the rebel army, which was endeavoring by advancing _via_ the Bristo station from the east and Thoroughfare Gap road from the west, to get in its rear. The major in command of the lines covering both roads, Bristo station and Warrenton pike, gathered up all the men who could be conveniently reached, and following the corps, left me in ignorance of our dangerous position and entirely at the mercy of the enemy. (This major was afterwards court martialed for conduct unbecoming an officer in the face of the enemy, and dismissed from the service.)