The topography of New Ulm presented an advantage for the Dakota, since the land rises some 200 feet out of the Minnesota River valley in two large steps (terraces), with wooded area to provide cover for an attack.

In 1851, the Santee Dakota people of Minnesota had been forced to cede to the government their lands of 24,000,000 acres (97,000 km2) under the terms of the Treaty of Traverse des Sioux.

In 1858, the U.S. government additionally purchased the half of the reservation lying north of the Minnesota River for $555,000, to be paid out annually over fifty years.

[6] After much debate a faction led by Little Crow resolved to declare war the next day, with the aim of driving all whites out of the Minnesota River valley.

After finding mutilated corpses and being fired upon, Roos realized that the attacks were much more serious than initially thought and returned to New Ulm.

In the meantime Franz Czeigowitz, a former Austrian soldier and New Ulm resident, organized about 50 poorly armed citizens into a defensive militia.

[14][1] Shortly after the first attack, Charles Eugene Flandrau and a relief force from St. Peter and Le Sueur reached New Ulm.

Captain William B. Dodd, second in command, was killed near the log blacksmith shop while leading soldiers beyond one of the barricades in an attempt to link up with a supposed reinforcement column - in reality, a body of Dakota masquerading as militia.

Realizing the seriousness of the situation, Flandrau and Nix led a charge out of the barricades down Minnesota Street and swept away the advancing Dakota.

Flandrau convened with his officers later that day and decided to evacuate the city (despite objections by Nix and others), due to a shortage of ammunition and food and the outbreaks of disease.

[19] William Watts Folwell, a Minnesota historian, remarked, "This was no sham battle, no trivial affair, but a heroic defense of a beleaguered town against a much superior force.