The reader may readily conceive the facility, therefore, with which, thus circumstanced, Sir Niel and his followers could, from the opposite side of the river, retard the advance of even a larger army than that of M’Fadyan. The difficulty of the pass is not perceptible till the angle of the rock is fairly turned, consequently the Irish army had no opportunity of covering their advance by discharging their missiles. They were obliged to follow each other singly; thus affording, as they came creeping along, fair marks for the arrows of the Scots, part of whom plied their deadly shafts, while others were engaged in throwing stones from their slings against the face of the rocks, and thus bringing down masses of the loose fragments upon the heads of their already embarrassed pursuers. The castle to which Sir Niel retired, though small, possessed great natural advantages. Situated on a rocky knoll at the edge of a deep ravine, it could only be approached from the road through which M’Fadyan had to advance, and that by means of a ladder which the party within always kept on their own side. When they wished to admit any one, a rope was thrown over that he might pull the ladder towards him; he then descended to the bottom of the ravine, when, placing the ladder against the opposite rock, in this manner he ascended and reached the castle.[102] When Sir Niel Campbell had determined on his line of retreat, he despatched Duncan of Lorn, and an old, but swift-footed Highlander, named Michael or Gillemichel, to acquaint Wallace of his perilous situation, and to crave his aid in driving the invaders from the country. Wallace, aware of the importance of preventing the establishment intended by Edward, lost no time in complying with the request of his old confederate; and Sir Richard Lundin having joined him with five hundred men, he now found himself enabled to march to the relief of the West Highlanders, at the head of two thousand soldiers. In Duncan of Lorn and his servant, Wallace had sure and intelligent guides. At that time nothing but intricate footpaths, known only to the natives, existed in the Highlands; and as they were often formed by deer-stalkers, while tracing their game, they frequently led through places both perilous and perplexing to the stranger.