At daylight I had reached the crest of hills occupied by the enemy an hour before, and, a few minutes before six, General Custer drove the rearguard of the enemy into the river at Williamsport. Learning from citizens that a portion of the enemy had retreated in the direction of Falling Waters, I at once moved rapidly for that point, and came up with this rearguard of the enemy at seven-thirty A. M., at a point two miles distant from Falling Waters. We pressed on, driving them before us, capturing many prisoners and one gun. When within a mile and a half of Falling Waters, the enemy was found in large force, drawn up in line of battle on the crest of a hill, commanding the road on which I was advancing. His left was protected by earthworks, and his right extended to the woods on our left. The enemy was, when first seen, in two lines of battle, with arms stacked within less than one thousand yards of the large force. A second piece of artillery, with its support, consisting of infantry, was captured while attempting to get into position. The gun was taken to the rear. A portion of the Sixth Michigan Cavalry, seeing only that portion of the enemy behind the earthworks, charged. This charge was led by Major Webber, and was the most gallant ever made. At a trot he passed up the hill, received the fire from the whole line, and the next moment rode through and over the earthworks, and passed to the right, sabring the Rebels along the entire line, and returned with a loss of thirty killed, wounded, and missing, including the gallant Major Webber, killed. I directed General Custer to send forward one regiment as skirmishers. They were repulsed before support could be sent them, and driven back, closely followed by the Rebels, until checked by the First Michigan and a squadron of the Eighth New York. The Second brigade having come up, it was quickly thrown into position, and, after a fight of two hours and thirty minutes, routed the enemy at all points and drove him toward the river. When within a short distance of the bridge, General Buford's command came up and took the advance. We lost twenty-nine killed, thirty-six wounded, and forty missing. We found upon the field one hundred and twenty-five dead Rebels, and brought away upward of fifty wounded. A large number of the enemy's wounded were left upon the field in charge of their own surgeons. We captured two guns, three battle-flags, and upward of fifteen hundred prisoners. To General Custer and his brigade, Lieutenant Pennington and his battery, and one squadron of the Eighth New York Cavalry, of General Buford's command, all praise is due. Very respectfully, your obedient servant,