Now gold was discovered in the mountains of what is now Montana — first at Bannack in 1862, then in richer deposits at Alder Gulch in 1863 and at Last Chance Gulch (the future Helena) in 1864.

The Montana goldfields quickly attracted tens of thousands of prospectors, merchants, gamblers, and the full supporting cast of a gold rush economy.

Getting to the Montana goldfields from the east was the problem.

The established route — what would become the Oregon Trail, swinging south and west through Wyoming before turning north through Idaho — was long, difficult, and expensive.

The alternative, a more direct path angling northwest from the North Platte River through the Powder River Country to Virginia City, was shorter but ran directly through the most productive Lakota bison range.

John Bozeman and John Jacobs had scouted the shorter route in 1863 and 1864, pushing through despite opposition from Lakota warriors who correctly understood that allowing a road through their country would not end well.