The Army planned this punitive expedition in retaliation for the "Grattan Massacre" in August 1854, and for raids by Lakota in its wake.

The battle was the defining engagement of a short war between the US and the Lakota Sioux over disputes concerning violations of the 1851 Treaty of Fort Laramie.

In March 1856, without authority to do so, commanding Gen. William Harney negotiated a peace treaty to stop further bloodshed with the Sioux.

He required a centralized tribal government among the Lakota, by which he intended to hold leaders accountable for the actions of bands.

While the battle was hailed by many newspapers as a heroic victory over the Indians, the New York Times called it a massacre and other critics decried it as "outright butchery," because of the killings of numerous women and children.

The lamentable butcheries of Indians by Harney's command on the Plains have excited the most painful feelings," wrote a New York Times correspondent in an 1855 dispatch from Washington.

"The so-called battle was simply a massacre, but whether those Indians were really the same who have cut off emigrant trains with so many circumstances of savage cruelty, or whether it is possible to distinguish between the innocent and the guilty in retaliating these outrages, are points on which we have no reliable information.

[3]Some others claimed that the battle was fought only to justify growth in the American army, which was being encouraged by Secretary of War Jefferson Davis.

The first decisive event that initialized the First Sioux war was catalyzed when a Mormon emigrant lost a cow while traveling with his party on the Oregon Trail; the animal wandered into a Brulé Lakota camp.

He first attempted to parlay with the Sioux chief, Little Thunder, but his demands to hand over the men responsible for the Grattan attack were rebuffed.

[citation needed] The American forces were victorious, killing 86 Sioux and taking 70 prisoners, mostly women and children.

The Sioux called Harney "The Butcher" for the battle at Blue Water, "the Hornet" for invading their territory, and "the Big Chief Who Swears" for the treaty he forced.