This able General now proposed to place guards in such a manner as should prevent the garrison in the castle marching out to surprise him, but his exertions were baffled by the want of judgment and incompetency of those beneath him in command. The guard was placed near the weigh-house at the foot of the Castle-rock, so that the battery of the half-moon, as it was termed, near the Castle-gate, bore upon it, and many of the guard within would have perished upon the first firing. This was not the only mistake. Mr. O'Sullivan, one of Prince Charles's officers, one day placed a small guard near the West Kirk, which was not only exposed to the enemy's fire, but conveniently situated near the sally-port, whence the besieged might issue and take the party there prisoners; for no relief could be sent to them in less than two hours' time, owing to its being necessary to pass round the whole circumference of the castle to arrive at that point. "I never," says Lord George Murray, "knew of that guard's being placed there, until they were taken prisoners." So severe a service was this blockade, that it was found necessary to relieve the guards, which were thus placed, by different corps who could not know the risk which they encountered. Desertions from the Jacobite army were among the most formidable evils with which Lord George had to contend. It was therefore important not to discourage the soldiery. In the midst of difficulty the high-minded Cameron of Lochiel came forward to offer his own person, and to risk his own regiment in this service. He agreed to take all the guards, and to relieve them with the soldiers of his own regiment, who were quartered for that purpose in the outer Parliament House. "I was with him," writes Lord George,[50] "when the guards were relieved, and the men did their duty exceedingly, especially when there was danger; and, when the fire was hottest from the castle, they kept their post with much resolution and bravery. Lochiel and I being much with them, gave them a heartiness that hindered them from complaining of a duty which was so hard, and which the rest of the army had not in their turns. We even placed new guards to keep the castle from sallying, as they seemed disposed; and Keppoch's regiment was brought into town to take some of the guards and support them. I lay in town for some nights, and was constantly visiting the guards and sentinels." The castle, nevertheless, seated on the precipitous rocks, which, steep as they are, have yet been "scaled by love and ambition,"[51] defied the blockaders. The Highlanders continued to keep guard in the weigh-house, and, stationing themselves in the Grass-market, the Smithfield as well as the Hay-market of Edinburgh, lying on the south side of the Castle-hill, awaited there the proceedings of the enemy.