He said he had visited Fort Sill when the Obama administration had detained migrant children there. “It was extremely well done, and they were extremely well cared for,” he said.

The Health and Human Services Department, which manages the Office of Refugee Resettlement, said that the plan for Fort Sill was only temporary, and that it would relieve pressure on an overcrowded system.

Still, turning to this particular base — which is home to the Army’s main artillery school, but is perhaps more famous for the people it once imprisoned — has touched a nerve.

In the 19th century, the Army held hundreds of Chiricahua Apache warriors who surrendered in the conflicts between Native Americans and the United States; Geronimo was one of them and is buried at the base. During World War II, a distraught Japanese detainee, Kanesaburo Oshima, was fatally shot there as he tried to climb the barb-wire fence, becoming a symbol of the imprisonment of Japanese-Americans. The United States formally apologized for the internment of Japanese-American citizens in 1988.

For descendants of the Japanese-Americans and the Native Americans who knew Fort Sill as a prison, not the verdant military training ground and national landmark it is today, the government’s new plan raised bitter questions about whether the nation had truly reckoned with its darker past. After the news conference on Saturday, the protesters moved to a nearby park when the police ordered them to leave the base.

“My grandfather was imprisoned on Fort Sill for 20 years with Geronimo,” said Jeff Haozous, 57, a member of the Fort Sill Apache tribe who stood in the sweltering heat at the protest. The one condition Geronimo demanded for surrender, he added, “was to keep the families together. The one promise they kept was they kept the families together.”