Let us examine, for a moment, how this premature engagement comes about. We left Tyler, accompanied by Richardson, with a squadron of Cavalry and a battalion of light Infantry making a reconnaissance, on Thursday morning the 18th, toward Blackburn's Ford. They approach within a mile of the ford, when they discover a Rebel battery on the farther bank of Bull Run--so placed as to enfilade the road descending from their own position of observation down to the ford,--strong Rebel infantry pickets and skirmishing parties being in front. Tyler at once orders up his two rifled guns, Ayres' Battery, and Richardson's entire Brigade--and later, Sherman's Brigade as a reserve. As soon as they come up,--about noon-he orders the rifled guns into battery on the crest of the hill, about one mile from, and looking down upon, the Rebel battery aforesaid, and opens upon the Enemy; giving him a dozen shells,--one of them making it lively for a body of Rebel Cavalry which appears between the ford and Manassas. The Rebel battery responds with half a dozen shots, and then ceases. Tyler now orders Richardson to advance his brigade and throw out skirmishers to scour the thick woods which cover the Bull Run bottom-land. Richardson at once rapidly deploys the battalion of light Infantry as skirmishers in advance of his brigade, pushes them forward to the edge of the woods, drives in the skirmishers of the Enemy in fine style, and supports their further advance into the woods, with the 1st Massachusetts Regiment. Meanwhile Tyler, discovering a favorable opening in the woods, "low down on the bottom of the stream," for a couple of howitzers in battery, sends Captain Ayres of the 5th U. S. Artillery, and a detached section (two 12-pound howitzers) of his battery, with orders to post it himself on that spot, and sends Brackett's squadron of the 2d Cavalry to his support. No sooner does Ayres open fire on the Enemy, than he awakens a Rebel hornet's-nest. Volley after volley of musketry shows that the Bull Run bottom fairly swarms with Rebel troops, while another Rebel battery, more to the Rebel right, opens, with that already mentioned, a concentrated cross-fire upon him. And now Richardson orders up the 12th New York, Colonel Walrath, to the left of our battery. Forming it into line-of-battle, Richardson orders it to charge through the woods upon the Enemy. Gallantly the regiment moves forward, after the skirmishers, into the woods, but, being met by a very heavy fire of musketry and artillery along the whole line of the Enemy's position, is, for the most part, thrown back in confusion--a mere fragment* remaining in line, and retreating,--while the howitzers, and Cavalry also, are withdrawn.