The armies on both sides were now receiving reinforcements. Louis XIV. sent seven thousand two hundred and ninety men of all ranks to the help of James, under the command of Count Lauzun. They landed at Cork in March, 1689, and marched at once to Dublin. Lauzun described the country as a chaos such as he had read of in the Book of Genesis. On his arrival at Dublin, Lauzun was appointed Commander-in-Chief of the Irish army, and took up his residence in the castle.

On the other hand, Schomberg's forces were recruited by seven thousand Danes, under a treaty which William III. had entered into with the King of Denmark. New detachments of English and Scotch, of Huguenots, Dutch, Flemings, and Brandenburgers, were also added to the allied army.

William landed at Carrickfergus on the 14th of June. He passed on to Belfast, where he met Schomberg, the Prince of Wurtemberg, Major-General Kirk, and other general officers. He then pushed on to Lisburn, the head-quarters of his army. He there declared that he would not let the grass grow under his feet, but would pursue the war with the utmost vigour. He ordered the whole army to assemble at Loughbrickland. He found them to consist of sixty-two squadrons of cavalry and fifty-two battalions of infantry—in all, thirty-six thousand English, Dutch, French, Danes, and Germans, well appointed in every respect. Lieutenant-General Douglas commanded the advance-guard—to which Rapin belonged—and William III., Schomberg, and St. Gravenmore commanded the main body.

William III. had no hesitation in entering at once on the campaign. He had been kept too long in London by parliamentary turmoil, by intrigues between Whigs and Tories, and sometimes by treachery on both sides. But now that he was in the field his spirits returned, and he determined to lose not a day in measuring swords with his enemy. He had very little time to spare. He must lose or win his crown; though his determination was to win. Accordingly he marched southward without delay.

William had been in Ireland six days before James knew of his arrival. The passes between Newry and Dundalk had been left unguarded—passes where a small body of well-disciplined troops might easily have checked the advance of William's army. Dundalk was abandoned. Ardee was abandoned. The Irish army were drawn up in a strong position on the south of the Boyne to arrest the progress of the invading army. James had all the advantages that nature could give him. He had a deep river in front, a morass on his left, and the narrow bridge of Slane on his right. Behind was a rising ground stretching along the whole of the field. In the rear lay the church and village of Donore, and the Pass of Duleek. Drogheda lay towards the mouth of the river, where the green and white flags of Ireland and France were flying, emblazoned with the harp and the lilies.

William never halted until he reached the summit of a rising ground overlooking the beautiful valley of the Boyne. It is about the most fertile ground in Ireland. As he looked from east to west, William said to one of his staff, "Behold a land worth fighting for!" Rapin was there, and has told the story of the crossing of the Boyne. He says that the forces of King James, lying on the other side of the river, amounted to about the same number as those under King William. They included more than seven thousand veteran French soldiers. There was a splendid body of Irish horse, and about twenty thousand Irish foot.

James's officers were opposed to a battle; they wished to wait for the large fleet and the additional forces promised by Louis XIV. But James resolved to maintain his position, and thought that he might have one fair battle for his crown. "But," says Rapin, "notwithstanding all his advantages—the deep river in front, the morass on his right, and the rising ground behind him—he ordered a ship to be prepared for him at Waterford, that in case of a defeat he might secure his retreat to France."

On the morning of the 30th of June, William ordered his whole army to move by break of day by three lines towards the river, about three miles distant. The King marched in front. By nine o'clock they were within two miles of Drogheda. Observing a hill east of the enemy, the King rode up to view the enemy's camp. He found it to lie all along the river in two lines. Here he had a long consultation with his leading officers. He then rode to the pass at Old Bridge, within musket-shot of the ford; next he rode westward, so as to take a full view of the enemy's camp. He fixed the place where his batteries were to be planted, and decided upon the spot where his army was to cross the river on the following day.

The Irish on the other side of the river had not been unobservant of the King's movements. They could see him riding up and down the banks, for they were not sixty yards apart. The Duke of Berwick, the Viceroy Tyrconnel, General Sarsfield, and other officers were carefully watching his movements. While the army was marching up the river-side, William dismounted and sat down upon a rising ground to partake of some refreshments, for he had been on horseback since early dawn. During this time a party of Irish horse on the other side brought forward two field-pieces through a ploughed field, and planted them behind a hedge. They took their sight and fired. The first shot killed a man and two horses close by the King. William immediately mounted his horse. The second gun was not so well aimed. The shot struck the water, but rising en ricochet, it slanted on the King's right shoulder, took a piece out of his coat, and tore the skin and the flesh. William rode away stooping in his saddle. The Earl of Coningsby put a handkerchief over the wound, but William said "there was no necessity, the bullet should have come nearer."

The enemy, seeing the discomfiture of the King's party, and that he rode away wounded, spread abroad the news that he was killed. "They immediately," says Rapin, "set up a shout all over their camp, and drew down several squadrons of their horse upon a plain towards the river, as if they meant to pass and pursue the English army. Nay, the report of the King's death flew presently to Dublin, and from thence spread as far as Paris, where the people were encouraged to express their joy by bonfires and illuminations." In the meantime William returned to his tent, where he had his wound dressed, and again mounted and showed himself to the whole army, in order to dissipate their apprehensions. He remained on horseback until nine at night, though he had been up since one o'clock in the morning.