August 15 marks the day that the Sell or Starve Act was signed in 1876. This law required the Sioux people to give up their claims to the Black Hills, or they would be denied food rations. As the Sioux were no longer allowed to live their traditional lifestyle, this would mean starvation.
In 1868, the US government had signed a treaty giving complete control over the area to the tribes in the area. When the famously genocidal General Custer discovered gold in the area, white settlers flocked to the area to mine for gold. The US army violated the treaty and protected the white settlers from reprisal. This finally resulted in the famous Battle of Little Bighorn, which is still a point of pride in native peoples today. General Custer was on his way to massacre a native village, but they were ambushed and every man was killed.
The genocidal government reacted by passing the Sell or Starve act. In February of the following year, they seized the land. The Sioux people still fight for the return of their land to this day. The land is sacred and they demand that the US government cede it back to them as was originally agreed. The courts have awarded them billions in damage, but the Sioux have unanimously refused to collect this money.