Brainerd studied at Yale for three years before being booted out for making uncharitable remarks about one of the professors. This ended his opportunity to become a pastor. The whole situation seemed to be rather unfair. But Brainerd bore up under the strain of it rather well. He eventually became licensed to be a pastor and was called to work among the Delaware Indians.
Considered to be a "pioneer of modern missionary work". "Brainerd began his ministry with the Indians in April, 1743, at Kannameek, New York, then ministered in Crossweeksung and Cranberry (near Newark), New Jersey. These were the areas of his greatest successes." He was a man who would get lost in prayer for the people that he was called to serve.
In fact the Indians that he was to serve sought to kill him before he even started. BUT didn't, he became known as "The Prophet of God" and here's why:
F.W. Boreham recorded the incident: But when the braves drew closer to Brainerd's tent, they saw the paleface on his knees. And as he prayed, suddenly a rattlesnake slipped to his side, lifted up its ugly head to strike, flicked its forked tongue almost in his face, and then without any apparent reason, glided swiftly away into the brushwood. "The Great Spirit is with the paleface!" the Indians said; and thus they accorded him a prophet's welcome. (source)