From Henry he learned much of the Indian wars in the West, and the strategic value of various points on the frontier, possession of which in the event of war he foresaw would be worth a king's ransom. Not least were details respecting Michilimackinac, the Mackinaw already referred to. Nearly half a century before, Henry, a native of New Jersey, of English parents--his ambition fired by tales of the fabulous fortunes to be made in the fur trade--obtained from the commandant at Montreal a permit to proceed west as a trader. He outfitted at Albany, and the following summer set out for Mackinaw. Meanwhile the Indian allies, under control of the great Pontiac, were fighting immigration and civilization. Between Fort Pitt--Pittsburgh-- and the Fox River, in Wisconsin, the home of the Sacs and Foxes, they had captured nine out of thirteen military posts, and were secretly planning the downfall of Fort Mackinaw. This was regarded as an impregnable post and vulnerable only through strategy--in Indian parlance another name for duplicity. Fort Mackinaw, as Brock well knew, was the most important trading _entrepot_ west of Montreal. It served a territory extending from the Missouri in the west to the far Kissaskatchewan in the north. On Henry's arrival his friendship was sought by an Indian chief, Wawatam. Between these two men a remarkable attachment developed. They became brothers by mutual adoption. At this time the fort was garrisoned by ninety British regulars. One day, outside the walls on the surrounding plateau, several hundred savages were encamped, ostensibly for purposes of trade, some of them killing time by playing the Indian game of ball--the _baggatiway_ of the red-man, _la jeu de la crosse_ of the voyageur. Henry, acting upon a veiled warning by Wawatam, suggested to the officer in command extra precaution. "I told him," said he, while Brock drank in every word, "that Indian treachery was proverbial." Now this recital was of the deepest interest to our hero, for Mackinaw, then in the possession of the United States, held the key to the Michigan frontier and control of the upper lakes. While the huge log fire that roared in the chimney cast light and shadow on polished wall and the oak beams of the big dining-hall, Brock puffed away at his huge _partiga_, weighing every word that fell from the bearded lips of the trader.