The Black Hawk War was a conflict between the United States and Native Americans led by Black Hawk, a Sauk leader. The war erupted after Black Hawk and a group of Sauks, Meskwakis (Fox), and Kickapoos, known as the "British Band", crossed the Mississippi River, into the U.S. state of Illinois, from Iowa Indian Territory in April 1832. Black Hawk's motives were ambiguous, but he was apparently hoping to reclaim land sold to the United States in the disputed 1804 Treaty of St. Louis.

U.S. officials, convinced that the British Band was hostile, mobilized a frontier militia and opened fire on a delegation from the Native Americans on May 14, 1832. Black Hawk responded by successfully attacking the militia at the Battle of Stillman's Run. He led his band to a secure location in what is now southern Wisconsin and was pursued by U.S. forces. Meanwhile, other Native Americans conducted raids against forts and colonies largely unprotected with the absence of the militia. Some Ho-Chunk and Potawatomi warriors took part in these raids, although most tribe members tried to avoid the conflict. The Menominee and Dakota tribes, already at odds with the Sauks and Meskwakis, supported the United States.

Commanded by General Henry Atkinson, the U.S. forces tracked the British Band. Militia under Colonel Henry Dodge caught up with the British Band on July 21 and defeated them at the Battle of Wisconsin Heights. Black Hawk's band was weakened by hunger, death, and desertion, and many native survivors retreated towards the Mississippi. On August 2, U.S. soldiers attacked the remnants of the British Band at the Battle of Bad Axe, killing many and capturing most who remained alive. Black Hawk and other leaders escaped, but later surrendered and were imprisoned for a year.

The Black Hawk War gave Abraham Lincoln his brief military service, although he saw no combat. Other participants who would later become famous included Winfield Scott, Zachary Taylor, Jefferson Davis and James Clyman. The war gave impetus to the U.S. policy of Indian removal, in which Native American tribes were pressured to sell their lands and move west of the Mississippi River to reside.