Above Kootenay plains, the river contracted to a width of barely fifteen yards, and so continued to the forks, at which point the canoes had to be laid up. From the forks, there was a splendid view of the mountains still ahead, their peaks more elevated and craggy than they had so far seen, for they were in fact the main range of the Rockies. Taking the left branch of the stream they followed it to within a mile of its end in Glacier lake. At this point, between Mount Balfour on the right and Mount Forbes on the left, was a gap opening to the west. Into this gap they turned. A march of two miles through heavy pinewood brought them to a rivulet whose waters flowed to the west. "May God in his mercy," says the pious explorer, "give me to see where its waters flow into the ocean and return in safety." Thus he marked out his programme for the next four years.

This rivulet (Blaeberry creek) descended sharply through a narrow, winding valley between the heights; and it was necessary for the party to force their way through the thick woods along the steep and rugged slopes, and to cross and recross the stream through water knee-deep, in order to reach the mouth. A full day's travel, however, brought them to the valley of the Columbia. The weather had done its work on the canoe built by Jaco Finlay; and it was quite unseaworthy. They had to halt while they scoured the woods for materials and built new canoes. Finally they embarked and paddled south up the Columbia until they came to its headwaters. There, a short distance from Lake Windermere, they hewed logs of heavy fir and built a cabin which they strongly stockaded on three sides, the fourth resting on the steep bank of the river. This was Old Kootenay House, the first trading post erected by white men on the waters of the Columbia.

In this remote spot, the safety of all depended upon the courage and resource of the leader. Additional supplies were needed from Rocky Mountain House, and Finan McDonald was sent back across the mountains to fetch them. Until the end of autumn, provisions were scarce, for the red deer and antelope had not yet descended from the higher levels, and the mountain goat was hard to shoot as he leapt from crag to crag. The party therefore relied on fish and the flesh of wild horses whose feeding grounds were not more than two miles from the house. For the purpose of trade, it was necessary to get in touch with the natives and to examine the country as well as possible. The season was late, but Thompson was able to make one short excursion with a chief of the Flatbow Indians.

When Finan McDonald rejoined his chief, he brought with him alarming intelligence. In the course of the summer, the brother of Old White Swan, a Blackfoot chief, had with his band assaulted and pillaged Fort Augustus, possessing himself of many guns, much ammunition and tobacco and various other articles. Whether or not he had murdered the traders at the Fort, McDonald could not say; but it was clear that the spirit of unrest and resentment against the whites which had for some time pervaded the whole Blackfeet confederacy was now coming to a head; and Thompson could hardly hope that he himself would escape serious trouble.

Trouble came rather sooner than he expected. The fort was not yet finished when twelve Piegan Indians appeared on foot from across the mountains. A month later twenty-three more arrived. These set up their tents along with the others just outside the gates. For over two months they hung about the stockade, making themselves very objectionable, and forcing the garrison to remain together within the walls. But Thompson had a small stock of dried provisions on hand, and he put his men on short rations, so that there might be no need to scatter over the country for hunting. For water, he let down two large kettles nightly from the steep river bank and this was enough for the daily needs of the post. Towards the end of October, two of the Indians disappeared from the group, and the garrison feared a general attack. Nothing, however, materialized, and before winter set in, the savages drifted quietly away.

Yet their peril was not yet over. One morning, two more Piegans presented themselves at the fort. Thompson was anxious, but he did not flinch. He showed them the strength of his stockades and bastions, the walls bored with loopholes for his muskets. "I know," he said, "that you are come as spies and intend to destroy us, but many of you will die before you succeed. Go back to your countrymen and tell them this." At the same time, he loaded them with presents of tobacco for their friends. A fortunate circumstance hastened their departure. Two of the Kootenay Indians came to the fort while they were there, and when they saw the Piegans, they glared at them like tigers. Meanwhile the little garrison watched and waited, six hardy voyageurs ready to die if necessary in order to make good the words of their chief. And while they waited, winter came on, covering the mountains with snow and placing them in safety.

It was some time before Thompson learned the details of his escape. The two Piegans were, as he guessed, the advanced guard of a large war party that was being formed at the instigation of the civil chief to crush the white men and the natives to the west side of the mountains before they became well armed. The war chief (Thompson's old friend Kootanae Appee) had opposed this venture. How, he urged, could they smoke to the Great Spirit for success, if without warning they invaded the lands of a people with whom for ten summers they had been at peace? Such, however, was the influence of the wilder spirits, that the old war chief was compelled to yield to their will.

In fifteen days about three hundred warriors under three chiefs assembled at the rendezvous named by Kootanae Appee, and under his leadership marched through the mountains to within twenty miles of the post. There they awaited the return of their scouts. It was not long before the latter arrived. The Kootenays, they said, were gathering under the white man to fight for the protection of their post. At the same time they presented the chiefs with Thompson's gifts, six feet of tobacco for Kootenae Appee, eighteen inches for each of the lesser chiefs, and a fine pipe of red porphyry with an ornamental stem in which to smoke it.

Thompson's knowledge of the Indians was thorough, and in this case, his guess as to their intentions had hit the mark. When the war chiefs heard his message of defiance, they were dumbfounded. "What can we do with this man," they exclaimed, "our women cannot mend a pair of shoes but he sees them" (alluding, of course, to Thompson's astronomical observations). Then the eldest of the three war chiefs, wistfully eyeing the tobacco, of which they had none, observed: "I have attacked tents, my knife could cut through them and our enemies had no defence against us. I am ready to do so again. But to go and fight against logs of wood that a ball cannot pierce, and with people we cannot see and with whom we are at peace, is what I am averse to. I go no further!" So saying, he slowly fitted the pipe to the stem and handed it to Kootenae Appee. Led by Kootenae Appee, they all smoked; and, having accepted Thompson's present, were unable to go further against him. Thus by his own resource and by the support of an old friend won in the days of his service for the Hudson's Bay Company, David Thompson prevented the destruction of the first trading post on the Columbia.

With the coming of spring began the work of exploring the country. Leaving McDonald in charge of Kootenay House, Thompson embarked with four voyageurs on the 20th of April, 1807, and paddled through Lake Windermere to the source of the Columbia. From thence, an easy portage of two miles across a grassy plain brought him to a fine stream flowing south, the Kootenay river of today. Launching his canoe, he proceeded to search for Indians.