CANNON BALL, N.D. — Lee Plenty Wolf knows the government wants him to clear out of the snowbound tepee where he stokes the fire, sings traditional Oglala songs and sleeps alongside a pair of women from France and California who came to protest an oil pipeline in the stinging cold. But he and thousands of other protesters are vowing to make what may be their last stand at Standing Rock.

The orders to evacuate the sprawling protest camp on this frozen prairie just north of the Standing Rock Sioux Reservation came down last week from the U.S. Army Corps of Engineers and the North Dakota governor’s office. After four months of prayer marches and clashes with law enforcement officials who responded with tear gas and water cannons, the protesters now have until Monday to leave.

The government said it would not forcibly remove anyone, but could cite people for trespassing or other offenses.

At the camp, defiance is rising like smoke from the stovepipe of Mr. Plenty Wolf’s tepee. People are here to stay. They are building yurts and hammering together plywood for bunkhouses and lodges. The communal kitchen stops serving dinner at 9:30 p.m.; it reopens a half-hour later as a sleeping space.