EXPLORING EXPEDITION. FROM THE DETROIT GAZETTE. Last Friday evening, Governor Cass arrived here from Chicago, accompanied by Lieutenant M'Kay and Mr. R. A. Forsyth,[151] both of whom belonged to the expedition--all in good health. [151] Major Robert A. Forsyth was a native of the Detroit Country, of Canadian descent, and born a few years after its transfer to the United States. At the time of the expedition, he was the Secretary of Governor Cass, and was admirably qualified to take a part in it, by his energy and perseverance, his indomitable courage, and his physical power and activity. Some of these traits of character were developed at an early age. He was but yet a lad at the time of the surrender of Detroit, and was so much excited by that untoward event, that he insulted the British officers in the fort by his reproaches, and so irritated them that one of them threatened to pin him to the floor with a bayonet. During the war upon the frontier, he was actively employed, and on more than one occasion distinguished himself by his conduct and courage. He was with Major Holmes at the battle near the Long Woods, and behaved with great gallantry. In 1814, he was sent with Chandruai, a half-breed Pottowatamie, and with a small party of Indians, to invite the various Indian tribes to come to Greenville, at the treaties about to be held by Generals Harrison and Cass, with a view to detach the North-Western Indians from British influence. On the route, they met a superior party of Indians, led by an officer of the British Indian Department, who attempted to take them prisoners. They resisted, and, by their prompt and almost desperate courage, drove off the British party. Forsyth distinguished himself in the contest, in which the British leader of the party was killed. Soon after the war, he was appointed Private Secretary to Governor Cass, and continued in that capacity for fifteen years, till the latter was transferred to the War Department. He accompanied the General in all his expeditions into the Indian country, and rendered himself invariably useful, having a peculiar talent to control the rough men who took part in these dangerous excursions. He was ultimately appointed a paymaster in the army, in which capacity he served in Mexico, where he acquired the seeds of the disorder which proved fatal to him in 1849. He will be long recollected and regretted by those who knew him, for the shining qualities of head and heart which endeared him to all his acquaintances.