But loth as he was to engage Mackay with the Highlanders alone, Dundee knew that he could not hope to keep them long together inactive. Provisions were running short. If they could not harry James's enemies, they would make free with their own. Dundee was particularly anxious to give no cause of offence to those clans whose neutrality he hoped to be able to turn into friendship. Already a serious prospect of disunion had threatened the little army. A party of the Camerons had made a raid on the Grants, in which a Macdonald of Glengarry had been killed. The man had become affiliated to the Grants, and had refused to join the muster of his own tribe. He had therefore forfeited all the right of clanship. Yet Glengarry, as much perhaps from policy as from any overpowering sense of kinship, demanded vengeance; and it needed all the combined tact of Dundee and Lochiel to prevent him from drawing out his men to attack the Camerons. When, therefore, Dundee learned that Mackay had left Inverness to join some reinforcements from Edinburgh, he determined on action. The troops Mackay expected to find in Badenoch were six hundred men of his own Scots Brigade under Colonel Ramsay. Ruthven Castle on the Spey was the place of meeting, and May 26th the time. But Ramsay had been detained in Edinburgh by an alarm of an invasion from France, and it was not till the 27th that he entered the Athole country. Here he learned that Dundee was on the march to meet him. The population did not seem friendly: he could get no news of Mackay; and on the whole he judged it prudent to retire to Perth. That he might do this with more speed he blew up his ammunition train, to prevent it falling into Dundee's hands. Mackay, who, as soon as he learned that Ramsay was fairly on the road, had marched with all speed from Inverness, was too late to save Ruthven Castle. It had been surrendered by the governor, Captain Forbes, on the 29th, and reduced to a heap of ruins.