Question: Midewin National Tallgrass Prairie is located on the site of a former United States Army arsenal that opened during which war?
Context: Sheyenne National Grassland is a National Grassland located in southeastern North Dakota in the United States, comprising 70446 acre of public land amid 64,769 acre of privately owned land in a region of sandy soils in the vicinity of the Sheyenne River in Ransom and Richland Counties.  It is the only National Grassland in the tallgrass prairie region of the U.S.  The grassland provides habitat for the largest population of greater prairie chickens in North Dakota, as well as the Dakota skipper butterfly, the western prairie fringed orchid, and numerous ferns, as well as grazing land for approximately 83 cattle ranchers. Tallgrass Prairie National Preserve is a United States National Preserve located in the Flint Hills region of Kansas, north of Strong City.  The preserve protects a nationally significant example of the once vast tallgrass prairie ecosystem.  Of the 400,000 square miles (1,000,000 km) of tallgrass prairie that once covered the North American continent, less than 4% remains, primarily in the Flint Hills.  Since 2009, the preserve has been home to the growing Tallgrass Prairie bison herd. The Liberty Arsenal, known by Federal authorities as the Missouri Depot was a United States Army arsenal at Liberty, Missouri in Clay County, Missouri.  The depot was seized twice by Southern partisans, once during the Kansas troubles in 1855, and again shortly after the outbreak of the American Civil War.  It was located generally west of the junction of Missouri Route 291 and old 210 Highway. Southeast Kansas is a region of the U.S. state of Kansas.  It can be roughly defined by Woodson County in the northwest, Bourbon County in the northeast, Cherokee County in the southeast, and Montgomery County in the southwest.  Geographically it is dominated by a broad rolling landscape located between the Flint Hills to the west and includes the Ozarks to the southeast.  Some notable towns there include Pittsburg, Parsons, Coffeyville, Independence, Chanute, Fort Scott, and Iola.  The region has a land area of 13,624.13 km² (5,260.30 sq mi) and a 2000 census population of 180,815 inhabitants.  It has 6.43% of the state's land area and 6.726% of its population.  It is dominated by a broad rolling landscape that includes the Ozarks.  It receives more precipitation than any other part of Kansas.  Southeast Kansas is located in the tallgrass prairie ecosystem of North America.  Originally inhabited by several Native American tribes, frontier towns largely dependent on cattle ranching, and mining, were wracked by violence over the issue of slavery both before and during the American Civil War.  Southeast Kansas offers one of the premier reconstructions of early life in the United States Army at Fort Scott National Historic Site. Joliet Army Ammunition Plant (JOAAP, formerly known as the Joliet Arsenal) was a United States Army arsenal located in Will County, Illinois, near Elwood, Illinois, south of Joliet, Illinois.  Opened in 1940 during World War II, the facility consisted of the Elwood Ordnance Plant (EOP) and the Kankakee Ordnance Works (KNK).  In 1945, the two were deactivated and combined forming the Joliet Arsenal.  The plant was reactivated for the Korean War and renamed Joliet Army Ammunition Plant during the Vietnam War.  Production of TNT ended in 1976, and the major plant operations closed shortly after in the late 1970s.  The facility briefly revived an automated load-assemble-pack (LAP) artillery shell operation that was managed by the Honeywell Corporation during the Reagan administration in the 1980s before it was finally closed. The Neal Smith National Wildlife Refuge is a federal national wildlife refuge located in Jasper County, Iowa, United States.  The refuge, formerly known as Walnut Creek, is named after Congressman Neal Edward Smith, who championed its creation.  It seeks to restore the tallgrass prairie and oak savanna ecosystems that once covered most of Iowa.  It has a herd of approximately 75 buffalo (bison) and 25 elk. The Midewin National Tallgrass Prairie (MNTP) is a tallgrass prairie reserve and United States National Grassland operated by the United States Forest Service.  The first national tallgrass prairie ever designated in the U.S. and the largest conservation site in the Chicago Wilderness region, it is located on the site of the former Joliet Army Ammunition Plant between the towns of Elwood, Manhattan and Wilmington in northeastern Illinois. The Charleston Arsenal was a United States Army arsenal facility in Charleston, South Carolina, seized by state militia at the outbreak of the American Civil War.  On June 21, 1996, it was added to the National Register of Historic Places as Porter Military Academy. The Hackmatack National Wildlife Refuge is a newly established United States national wildlife refuge that will include noncontiguous properties, especially tallgrass prairie patches, wetland properties, and oak savanna parcels, located in the northwestern region of the Chicago metropolitan area and the southern part of the Milwaukee area.  The refuge's boundaries encompass parts of McHenry County, Illinois, and Walworth County, Wisconsin.  The refuge will be operated by the United States Fish and Wildlife Service, known as USFWS.  85 percent of the refuge will be in Illinois, and 15 percent in Wisconsin. Nine Mile Prairie (named for its location 5 mi west and 4 mi north of downtown Lincoln) is a 230 acre tract of conserved tallgrass prairie in Lancaster County, Nebraska, United States.  Except for one small portion of it that was farmed as recently as the 1950s, Nine-Mile Prairie has never been plowed (some of the land has at times been grazed as recently as the 1960s).  As such, it is one of the largest areas of virgin tallgrass prairie in the state of Nebraska.  It has been listed on the National Register of Historic Places since 1986.
Answer: World War II