Baffled in his efforts to succor the town from the side of Lough Foyle, Kirke divided his fleet and with one part of it doubled Malin Head, sailed up Lough Swilly, and established a garrison of 800 men near Rathmelton, a few miles west of Derry. The place was well selected for his purpose; which was to attract the attention of the besiegers, and cause them to withdraw some of their forces from the side of the Foyle. This movement was observed by de Rosen, who, instead of drawing his forces from the water-side, ordered Berwick from Enniskillen to check the movements of Kirke, and dislodge him, if possible, without weakening the forces stationed at the obstructions in the river; and Berwick, as already indicated, abandoned Enniskillen, and arrived at Rathmelton, with a force of 1,200 horse, about the 22d of July. The position occupied by Kirke was one of great natural strength. The inlets of the Lough indented the country in all directions, and extended up to within three or four miles of Derry, presenting almost insuperable difficulties to an attacking force; and, on one of its peninsular mazes, he was found strongly intrenched under the protection of his frigates. Berwick spent a whole day in trying to dislodge him, but without effect, when he retired to an adjacent height, and contented himself with watching his movements, and confining him to his intrenchments. But Kirke succeeded in his object. Notwithstanding the vigilance of Berwick, he threw both men and munitions into Enniskillen; partially relieved Derry; and conjuring the governor to hold out yet a little longer, sailed out of Lough Swilly, and joined the fleet at the Foyle, while Berwick united his command to the force of the besiegers.