At present there was no need to press offensive operations. Middleton was still in Sutherland, and from Dingwall Morgan was watching him, ready to fall on him if he attempted to join the Lochaber chiefs. In the middle of May Monk moved to Stirling to see that all the outlets from the hills were sufficiently secured to prevent forays in that direction. Having ordered the construction of redoubts and the staking of fords wherever necessary, he joined the first column at Kilsyth in order to more deeply mark the south-west limit of his southern area by operations in the Ben Lomond hills. First, however, an important step was taken. A column, consisting of two thousand men and furnished with all necessary materials for establishing the fourth base, was being secretly organised in Ireland to seize Inverlochy. The time was now ripe for the attempt, and Colonel Brayne was despatched to bring it over. This done, Monk commenced his work. The difficulties of the undertaking at once declared themselves. The moment he moved, Glencairn, who occupied the Ben Lomond country, began raiding in his rear and stopped him. But the veteran of the Irish wars had learnt when to be bold, and without hesitation he flew at his enemy's throat. Advancing resolutely over the Kilsyth hills and up the headwaters of the Forth into the heart of the Ben Lomond range, he compelled Glencairn to concentrate and occupy a strong position at Aberfoyle. Here Monk attacked him. Again and again he was repulsed. But the discipline of the "red soldier" told at last, and Glencairn had to give way. The hills were cleared, every boat on the loch destroyed, and the western boundary of the southern area completed with an impassable stretch of water from Argyle's country to the banks of the Clyde.