Final answer:
The Battle of Wounded Knee occurred in December 1890 when Army troops captured some of Sitting Bull's followers, leading to the massacre of Native American civilians.
Step-by-step explanation:
The occurrence in December 1890 when Army troops captured some of Sitting Bull's followers was the Battle of Wounded Knee. The Battle of Wounded Knee resulted in the massacre of Native American civilians. The troops surrounded the Native American encampment and when they attempted to disarm the Sioux, a shot was fired which led to confusion and heavy fire from the troops. An estimated 150 to 300 Sioux men, women, and children were killed during this attack.