On the 23d, William's artillery having arrived, he moved forward. The same day King James retired to Ardee, where he was met by his train, and drew up in a strong position in the direct route between William and the capital. William, still advancing, crossed the mountains between Newry and Dundalk, and, observing the situation of the Irish army, divided his own into two bodies for the purpose of flanking it, or forcing it into the plain, where his great numerical superiority would render victory certain. Seeing this, King James continued gradually to fall back; on the 29th, he crossed the Boyne, at Drogheda, and, drawing up his army on the heights of Donore, overlooking that river, he there awaited the enemy. CHAPTER IX. THE BATTLE OF THE BOYNE. The Boyne, which finds its head-waters near Carbery, in the County of Kildare, takes a meandering course towards the west and north, until it enters Meath, through which it flows in a north-easterly direction through Trim, Navan, Slane, and Drogheda, four miles below which it falls into the Irish Sea. At tide-water it is navigable to Navan, a distance of nineteen miles, for barges of fifty tons burden; but at low-water, from Navan to Slane, it is a shallow stream, brawling over a rocky bottom of a few yards in width; and from that to Old Bridge it is fordable by horse and foot at almost every rood of its length. Below Slane, its course is due east for nearly a mile, when, dipping abruptly towards the south, it takes a semicircular sweep of nearly three miles to Old Bridge, and the curve so formed embraces its memorable battle-ground. The northern bank, for nearly half a mile back, is high and firm down to the water's edge, while the opposite one is low and sedgy, and the ground behind it broken, back to the base of Donore, which is over a mile from its mid-current:--the chord of the arc indicated is nearly two miles, and the distance from Old Bridge to Slane, in a direct line, is somewhat under three. On the evening of the 29th, when James crossed the river, the distance between his rear-guard and William's advance, was about eight miles, and on the morning of the 30th the latter appeared, and halted his army facing the concave bend of the river, behind a line of hills which partially concealed it from observation, while awaiting his artillery, which was still some miles in his rear.