This was the grizzly bear, which they were the first white men to discover.

They called it indifferently the grizzly, gray, brown, and even white bear, to distinguish it from its smaller, glossy, black-coated brother with which they were familiar in the Eastern woods.
They found that the Indians greatly feared these bears, and after their first encounters they themselves treated them with much respect.

The grizzly was then the burly lord of the Western prairie, dreaded by all other game, and usually shunned even by the Indians.

In consequence it was very bold and savage.

Again and again these huge bears attacked the explorers of their own accord, when neither molested nor threatened.
They galloped after the hunters when they met them on horseback even in the open; and they attacked them just as freely when they found them on foot.