Arkansas Post National Memorial is a protected area in Arkansas County, Arkansas in the United States. The National Park Service manages of the land, and the Arkansas Department of Parks and Tourism manages a museum on the remaining grounds. Arkansas Post was the first European settlement in present-day Arkansas when Henri de Tonti established it in 1686. The memorial commemorates the history of European-American settlers who inhabited the small entrepôt as the first Arkansans, an American Revolutionary War skirmish in 1783, the first territorial capital of Arkansas from 1819–1821, and a Civil War Battle in 1863.
Arkansas Post was founded in 1686 by Henri de Tonti as a trading post at the site of a Quapaw Indian village named Osotouy, near where the Arkansas River enters the Mississippi River. There the French conducted the first documented Christian services in present-day Arkansas. The site became a strategic point for France, Spain, the United States, and the Confederate States at different times during its history. During its time as a trading post there were three known locations and possibly a fourth as the area was prone to flooding.
In 1803 Arkansas Post became a part of the United States as part of the Louisiana Purchase. The post was selected as the first capital of the new Arkansas Territory, and became the center of commercial and political life in Arkansas. When the territorial capital was moved in 1821 to Little Rock, Arkansas Post lost much of its importance.
During the American Civil War, the Post was an important strategic site, as it was at the confluence of two major rivers. In 1862, the Confederate Army constructed a massive defensive earthwork known as Fort Hindman, named after Confederate General Thomas C. Hindman. It was located on a bluff 25 feet above the river on the north bank, with a mile view up and downriver. It was designed to prevent Union forces from going upriver to Little Rock, and to disrupt Union movement on the Mississippi. On January 9–11 of 1863, Union forces conducted an amphibious assault on the fortress backed by ironclad gunboats. They destroyed both the fort and the civilian areas.
The former site of Arkansas Post was made into a state park in 1929. It is located on a peninsula in the Arkansas River in Arkansas County. On July 6, 1960 the site was designated a National Memorial, and a National Historic Landmark on October 9, 1960.
As with all National Historic Landmarks, Arkansas Post was administratively listed on the National Register of Historic Places on October 15, 1966.