Question: For which war was the ammunition plant, located in Illinois, and now a tallgrass prairie reserve; the largest conservation site in the Chicago Wilderness region, originally opened?
Sentence (from "Midewin National Tallgrass Prairie"): The Midewin National Tallgrass Prairie (MNTP) is a tallgrass prairie reserve and United States National Grassland operated by the United States Forest Service.
Relevant evidence: Yes