Sherman knew that as long as the Sioux hunted buffalo, they’d never surrender to life with a plow. In a letter to Sheridan, dated May 10, 1868, Sherman wrote that as long as buffalo roamed those parts of Nebraska, “Indians will go there. I think it would be wise to invite all the sportsmen of England and America there this fall for a Grand Buffalo hunt, and make one grand sweep of them all.”

By now the buffalo that once covered all the Great Plains were hewn into two giant herds––one in the north, and one in the south. Still, the brown herds could overwhelm, and when Sheridan asked a trader how many buffalo he thought lived in the southern herd, the man said 10 billion. Obviously, that was absurd. But if the Army planned to slaughter all buffalo and starve the tribes into submission, it’d take more time and men than Sheridan had. Still, there’s evidence he thought it the best option: In October 1868, Sheridan wrote to Sherman that their best hope to control the Native Americans, was to “make them poor by the destruction of their stock, and then settle them on the lands allotted to them.”

Soon Sherman would have help. But along with the Fort Laramie Treaty, the U.S. had also signed the Medicine Lodge Treaty in 1867 with tribes in the south. So for the moment, The Indians Wars had paused.

In the lull, enlisted men like Cody found other ways to stay busy, and to make money. Cody had joined the Cavalry at 17, and he earned the name “Buffalo Bill” because in one 18-month stretch he claimed to have killed 4,280 buffalo. In 1870, a bull hide sold for $3.50. One frontiersman, Frank Mayer, figured if he spent 25 cents on each round of ammo, then “every time I fired one I got my investment back twelve times over.”

Buffalo were slow-grazing, four-legged bank rolls. And for a while, there were plenty. Then in 1873 an economic depression hit the country, and what easier way was there to make money than to chase down these ungainly beasts? Thousands of buffalo runners came, sometimes averaging 50 kills a day. They sliced their humps, skinned off the hides, tore out their tongues, and left the rest on the prairies to rot. They slaughtered so many buffalo that it flooded the market and the price dropped, which meant they had to kill more. In towns, hides rose in stacks as tall as houses. This was not the work of the Army. It was private industry. But that doesn’t mean Army officers and generals couldn’t lean back and look at it with satisfaction.

“I read that army commanders were even providing bullets to these hunters,” said Andrew C. Isenberg, author of The Destruction of the Bison, and a professor of history at Temple University. “The military looked at what the private sector was doing and they didn’t need to do anything more than stand back and watch it happen.”

Isenberg said though it was never official policy to kill buffalo in order to control Native Americans on the plains, the Army was certainly conscious about it. And at least in action, Isenberg said, “they were extremely explicit about it.”