On receipt of these orders, Sarsfield, at the head of three troops of horse, one of dragoons, and three battalions of foot,--a force of about five hundred men,--cleared the country along the south-east of the lake, and arrived at Belturbet on the 10th of June. Here he received an order from de Rosen to march forthwith to Omagh, about twenty-five miles north-west of Enniskillen, to protect the Irish besieging army at Derry against rebel attacks from that quarter, and proceeded at once to execute his commission. Southerland, with the remainder of his command--about 1,200 men--advanced through the south of Leitrim, and doubling Lough Oughter, reached the vicinity of Belturbet on the 16th of June. Here he found that Sarsfield had departed for Omagh, and that he was left to cope alone with the united commands of Hamilton, Wolseley, and Lord Blaney. On the 18th, he was informed by one of his spies that the enemy, 15,000 strong, knowing his condition, were about to seize a narrow pass, through which he had advanced, and to attack him in front and rear, with the intention of capturing or annihilating his force before the arrival of Mountcashel.[18] On receipt of this information, Southerland, leaving Lieutenant-Colonel Scott and two hundred and eighty men in the churchyard of Belturbet to check the pursuit, withdrew in the night, and, by a skilful movement, brought his command in safety to Sligo. The Enniskilleners, baffled in their design, then turned their whole force against Scott, who, after a stubborn contest of two hours, was compelled to surrender: and all the supplies of the garrison, eighty dragoon-horses, seven hundred muskets, and a considerable quantity of gunpowder, fell into the hands of the enemy. Berwick left Derry on the 21st, and, at the head of his four hundred dragoons, marched rapidly to the town of Donegal, where three hundred of the enemy from Ballyshannon were forming magazines. He approached their position in the night; attacked them at daybreak; killed many, forced the rest to the shelter of the castle; burned the magazines; and marched off with a booty of 1,500 cattle. Being shortly after joined by two regiments of horse and four battalions of foot,[19] which swelled his command to 1,200 men, he advanced, and on the 6th of July formed an encampment at Trellick, about nine miles north-east of Enniskillen. On the 13th, he advanced with a party to reconnoitre the country and the fortifications of the town, when he was ambushed by a force of two hundred foot and one hundred horse, and attacked with great vigor. But notwithstanding the suddenness of the onset, he turned on them; killed all but six of the infantry; drove the horse within their intrenchments, and returned with a captain, a lieutenant, two pair of colors, and the arms of the slain.