Arikara raiders "attacked the Missouri Fur Company's Fort Recovery [a trading post for the Sioux] and killed two traders" in the beginning of 1823.

When Lewis and Clark reached Arikara settlements in 1804, the inhabitants had not shown hostility to the expedition, but in 1806, when an Arikara leader died during a trip to the United States capital, many Arikara believed that Americans were involved in his death.

Eventually, as a result of the growing activity of fur trading companies, contact between Arikara and white merchants had become more frequent, and skirmishes eventually followed.

The Sioux, both Yankton and Yanktonai east of the Missouri and Lakota on the west side, have for long been at war with the Arikara, interrupted by short truces on Sioux terms.

The Arikaras in question are living in a double village on the west shore of the Missouri, six or seven miles upstream from the mouth of Grand River.

A small creek separates the two fortified villages of earth lodges, each with a heavy frame of wood.

Colonel Henry Leavenworth leaves Fort Atkinson (now in Nebraska) with two hundred and twenty men, joined by more than seven hundred Yankton, Yanktonai and Lakotas in the United States' first Indian war west of the Missouri.

The Arikara retreat to their fortified village.

The disappointed Sioux soon leave the battlefield.

The Arikara escape at night, and angry fur traders set their empty lodges ablaze the next morning.

The United States responds with a combined force of two hundred and thirty soldiers of the 6th Infantry, seven hundred and fifty Sioux allies, and fifty trappers and other company employees under the command of Lieutenant Colonel Henry Leavenworth, Fort Atkinson, present-day Nebraska.

The seven hundred and fifty warriors are part Yankton and Yanktonai Sioux, part western Sioux from the Brule, the Blackfeet and the Hunkpapa divisions.

The native force receives promises of Arikara horses and spoils, and with the enemy's villages fallen new ranges will open for the Sioux.

Colonel Leavenworth arrives at the Arikara villages on August 9 and commences the attack using his Sioux cavalry, but this is held off by the Arikara.

On August 10 Leavenworth orders an artillery bombardment.

This is largely ineffective, the shots falling beyond the villages, at which point Leavenworth orders an infantry attack.

Like the Sioux auxiliaries, the regular infantry also fails to break into the villages.

They leave the battlefield with some captured horses and laden with corn taken from the farming Indians' fields.

On August 11 Leavenworth negotiates a peace treaty.

"In making this treaty, I met with every possible difficulty which it was in the power of the Missouri Fur Company to throw in my way."

Fearing further attacks, the Arikara leave the village that night.

Leavenworth sets off to return to Fort Atkinson on August 15.

The Arikara village is burned behind him by resentful members of the Missouri Fur Company, much to Leavenworth's anger.

The US Army suffers the first casualties in the West during the Arikara War; seven people drown in the Missouri.

The causes of the Arikara War are not well recorded, but the trading relationship of the Arikara with white traders is certainly a factor.

The Arikara live in permanent settlements for most of the year where they farm, fish and hunt buffalo on the surrounding plains.

However, this is insufficient to sustain them and they rely on being a center of trade with neighboring tribes to survive.

Ashley's expedition to directly acquire furs and pelts cuts out the Arikara in their role as trading middle-men and is thus a direct threat to their livelihood.

There is also the issue of their desire to have a trading post on their territory so that they can have easy access to manufactured goods.

They resent the fact that their long-time enemies, the Sioux, have such posts, but they do not.

Ashley had been asked to set up a trading post when he was in the area in 1822.

Not wishing to limit his operations by having to maintain a permanent base, Ashley had instead promised the Arikara that he would have the goods they asked for shipped to them directly from St. Louis.

Ashley had not made good this promise at the time of his 1823 expedition, and possibly never intended to.

A further source of resentment, although probably not a direct cause of the war, had been the death of the Arikara chief Ankedoucharo during a visit to Washington in 1806.

Ankedoucharo had died of natural causes, but it was widely believed among the Arikara that he was deliberately murdered.

The initial episode at the Arikara villages on June 2 reaches international level when some hinted, that the British Hudson's Bay Company is the mastermind behind it all.

The plot, so some believe, is to put a wedge between the American fur traders and the Arikaras.

The British deny this.