13h 54min, sep 2, 1862 y - U.S.-Dakota War Battle of Birch Coulee
When Sibley and his men were at Fort Ridgely, he sent some to go locate any more people who need burying. When they got to Birch Coulee, the burial party got attacked by Dakota soldiers. That was the hardest fought battle in the war. Dakota soldiers kept the U.S. soldiers surrounded for three days before help came to get them.
Added to timeline:
Dakota War Timeline