WATCH | Darshan Black Moon and her husband Layne Laststaur of the Cheyenne River Sioux tribe are among the estimated 7,000 people at the Oceti Sakowin camp of the Standing Rock Sioux tribe in North Dakota.
They, like so many others, stood their ground even as sub-zero temperatures descended on them.
Sunday, the couple who's been protesting the Dakota Access Pipeline for four months saw that their efforts to stop construction were not in vain because the U.S. Army Corps of Engineers announced that it will not grant the easement to cross Lake Oahe for the proposed pipeline.
A huge assembly has been protesting the Dakota Access Pipeline since April 2016. The protesters are comprised of indigenous tribes and other activists from around the world, including hundreds of veterans.
With sub-zero temperatures at night, many gathered around the sacred fires that burned constantly. Drumming and singing went on throughout the night as many prayed for a peaceful resolution.
Long lines of cars filled with veterans entered the camp throughout Saturday. The vets came to serve in whatever way they could, including setting up Army tents and hauling wood for the campsites.
Protesters, or "water protectors," who have been living at the camps for months are staying in tents, teepees, mobile homes, yurts and their cars to endure the extreme cold spell.
The camp has several tents where food is prepared and served by volunteers during the day and night feeding droves of people at no charge.
No drugs, alcohol or weapons are allowed at camp, nor any recordings of prayer ceremonies, dances or musical performances.
Veterans poured into the area over the weekend.
If the U.S. Army Corp of Engineers had approved the pipeline's proposed route, it would have crossed under the Missouri River, threatening the water supplies of Standing Rock, and many more tribes and communities including the Cheyenne River Sioux to the south.
The Dakota Access Pipeline is being built by the Dallas-based Energy Transfer Partners. It is a $3.8 billion venture to transport crude oil through the Dakotas, Iowa, and Illinois.
Until recently, President-elect Donald Trump had a financial stake in Energy Partners; he sold his shares in that company but still has invested in Phillips 66, which will have a 25 percent ownership stake in the pipeline when it's completed. President Obama said the pipeline may be rerouted.
The protesters have been instructed to leave the area by Monday. The North Dakota government said it would not force anyone to leave, but some clashes between protesters and law enforcement have been violent.
Sen. Elizabeth Warren urged the Corps to accommodate the Sioux requests.
Here's a look at the camp from above.
Some protesters have come from as far away as Switzerland.