Great article in this month's Armchair General magazine by Greg Michno. Some notable quotes:
"The Dakota War exceeded the 'Great' Sioux War in numbers, casualties, cost, and significance."
"Even Custer's famous Little Bighorn disaster can't claim the title of the worst Indian defeat of U.S. Soldiers; that unfortunate titleholder is the November 4, 1791, Battle of the Wabash, where General Arthur St. Clair's force was nearly annihilated (630 killed, 280 wounded) by Indians under Little Turtle and Blue Jacket."
Killdeer Mountain: "With 1,600 lodges and 8,000 Indians (Sully claimed 5,000 warriors, but Sioux sources say 1,600), this village was larger than the oft-ballyhooed 'great' Indian village attacked by George Custer's 7th Cavalry at Little Bighorn in 1876. Sully's victory cost 15 Soldier casualties while Indian losses were 150."
"In August 1864, in North Dakota's Badlands, Sully faced over 10,000 Indians. The fighting produced 109 Soldier casualties, and the Indians lost about the same number."
At Little Bighorn: "The Indians lost, as most, 120 killed or wounded - about one-third the number of their 1863 losses at Whitestone Hill."