Thus matters dragged on quite indecisively until June, 1690, when King William landed at Carrickfergus with a mixed force of English, Scottish, Dutch, Danish, Swedish and German troops, and joined his forces to the remnant of Schomberg's army. James, as we saw, had disbanded his army on breaking up his camp in the previous autumn, and had made no effective effort to get a new army together. Nor could he have used a strong army, had he possessed one. Nevertheless James marched north with such troops as were available, leaving Dublin on June 16th. He took up a strong position on the borders of Ulster and Leinster, thus blocking William's way south to the capital, only to abandon it again on the news of William's approach, when he retired to Drogheda and encamped there. He thus gave the whole advantage of initiative into the hands of his opponent, a brave man and a skillful general.
James seems to have hoped that William's army would be mowed down by disease, as Schomberg's had been in the preceding campaign. And there is reason to believe that Tyrconnell, foreseeing the defeat of James, wished to avoid any serious fighting, which would be an obstacle in his way when he sought to patch up a peace with the victor and make terms for himself. But his opponent was inspired by a very different temper, and William's army advanced steadily southwards, to find James encamped on the southern bank of the Boyne.
There were several fords by which William's army would have to cross on its way south. But James was such an incapable general that he did not even throw up trenches to defend the fords. William's army arrived and encamped on the north bank of the river, and the next day, June 30th, was employed in an artillery duel between the two armies, when considerable injury was inflicted on William's forces, although he was far stronger in artillery than his opponent. During that night, James, already certain of defeat, sent away most of his artillery to Dublin, leaving only six guns with his army on the Boyne.
It seems tolerably certain that, when the battle began again next day, William's army numbered between forty-five and fifty thousand, with the usual proportion of cavalry,--probably a tenth of the whole. James, on the other hand, had from twenty to twenty-five thousand men, about a tenth of them, probably, being mounted; he had, by his own fault, only six guns against about fifty in William's batteries. William's line of battle was formed, as usual, with the infantry in the center and the cavalry on the wings. He gave the elder Schomberg command of the center, while Schomberg's son, with the cavalry of the right wing, was sent four or five miles up the river to Slane, to cross there and turn the left flank of the opposing army. William himself led the cavalry on the left wing, and later on in the battle, descending the river, crossed at a lower ford. He could thus attack the right flank of his opponent; the infantry composing the center of his army advancing, meanwhile, under cover of a heavy artillery fire, and forcing the fords of the Boyne.
The river is shallow here, and in the middle of summer the water is nowhere too deep for wading, so that it was a very slight protection to the army of James. A better general would at least have chosen a stronger position, and one which would have given him some manifest advantage. Such positions were to be found all along the road by which William had advanced from Carrickfergus. The country on both sides of the Boyne is flat; rolling meadows with the shallow river dividing them--a country giving every opportunity to cavalry.
William's right, under the younger Schomberg, made several unsuccessful attempts to cross the river at Slane, being repeatedly beaten back by Arthur O'Neill's horse. Finally, however, the way was cleared for him by a vigorous cannonade, to which O'Neill, having no cannon, was unable to reply, and William's right wing thus forced the passage of the Boyne.
William's center now advanced, and began the passage of the river, under cover of a heavy artillery fire. Every foot of the advance was stubbornly contested, and such headway was made by the Irish troops that Schomberg's bodyguard was scattered or cut to pieces, and he himself was slain. The center of William's army was undoubtedly being beaten back, when, crossing lower down with eighteen squadrons of cavalry, he fiercely attacked the right flank of the Irish army and thus turned the possibility of defeat into certain victory. That the Irish troops, although outnumbered two to one and led by a coward, fought valiantly, is admitted on all sides. They charged and re-charged ten times in succession, and only gave way at last under pressure of greatly superior numbers. The retreat of the Irish army was orderly,--the more so, doubtless, because the former king of England was no longer among them, having most valiantly fled to Dublin, and thence to Kinsale, where he took ship for France, leaving behind him a reputation quite singular in the annals of Ireland.
Within a week after the battle, the Irish army, which had preserved order and discipline even in the face of the flight of James, occupied Limerick, and made preparations to hold that strong position, with the untouched resources of the western province behind them, and the hope, unshaken by their rude experience, that the runaway king might reinforce them by sea. Through all the events that followed, presently to be narrated, it must be understood that Tyrconnell was steadily seeking to undermine the resolution of the Irish army, hoping the sooner to make his peace with King William, to secure his Irish estates, and, very possibly, be appointed Lord Lieutenant of Ireland, under the new king.