The United States and Territories were in great upheaval in the middle of the 19th century. Before 1860, the United States was a nation divided into three distinct economic and geographical areas, the industrial North, the slave holding, and agrarian South and the distant agricultural and mineral rich Pacific coast. The divided nature of the United States also colored the nation's relations with the American Indian tribes and nations who still existed as independent entities on the periphery of the organized territories and states, as well as those American Indians who lived in the unorganized void between the Pacific states and the rest of the Union.

Rather than a single vast war between Whites and the American Indians, or between Europeans and the Indians, the true nature of the colonization, settlement and conquest of North America by those of European heritage was a chaotic series of military actions, responses, treaties, and peace. After the creation of the United States in 1787, following the ratification of the Constitution, conflicts with American Indian tribes and nations took place in different phases and different areas. The sparse population and limited infrastructure coupled with the strategic nature of the Northern Great Plains to the United States created a theatre that was different in nature from the campaigns in the Southeast, Southwest, Pacific, or the Great Basin.

From 1800 through 1865, the migration of Europeans across the Great Plains was largely one of travel to the Pacific Coast. While the United States laid claim to the interior for the most part population growth occurred along the Eastern Seaboard, Ohio Valley and Southeast, following the Indian Removals, Secession of Texas from Mexico and the Mexican War the population center of the United States shifted west. However, the Northern Great Plains remained free of migration pressures from the European settlers.

Following the American Civil War, the dynamics of relations between the European settlers and American Indians changed. Prior to 1860, relationships between local governments and resident American Indian groups were largely limited to providing safe transportation routes to the Pacific Coast and Great Basin, it was a time where tactical situations were the norm, and strategic realities were inconsequential. Following the American Civil War, the spread of settlers west and the development of the Transcontinental Railroad routes created pressure on the traditional hunting lands of the Plains Indians which in turn created friction between the resident Indian groups, the Army and European settlers. A larger United States Army, coupled with an experienced and emboldened Officer Corps, led to new operational tactics and tempo following the War, as a result the long low intensity conflict from 1862 through 1890 on the Northern Great Plains saw a sea-change in how the wars between the Great Plains Indian Tribes and the United States were fought.

As the United States shifted to a style of warfare to break the military strength of the Plains Indians with tactics, albeit on a smaller scale and used to break the Confederacy from 1863-'65, gone were the reactionary and punitive raids by small units, they were replaced by large raids focused on breaking the Plains Indian's power. The Plains Indian's own Winter count records show that even during the pivotal year 1876, bands of Plains Indians sided with and used the United States Army to settle differences with other Tribes.

Geography and Demographics of the 19^th Century Great Plains

The Great Plains is the broad expanse of prairie that lies east of the Rocky Mountains in the United States of America and Canada and generally west of the Mississippi River. The Plains cover all or parts of the states of New Mexico, Texas, Oklahoma, Colorado, Kansas, Nebraska, South Dakota, North Dakota, Wyoming, Montana and the Canadian provinces of Alberta, Manitoba and Saskatchewan. Northern Great Plains refer to the elevated region of the Great Plains generally west of the 100th meridian, which roughly corresponds with the line west of which precipitation falls to less than 20 inches per year. The High Plains are semiarid with short grass prairie and scrub vegetation covering the region, with occasional buttes or other rocky outcrops scattered throughout the region. The region today contains eastern Colorado, western Kansas, western Nebraska, central and eastern Montana, parts of western South Dakota and North Dakota are included as is eastern Wyoming. From east to west, the High Plains rise in elevation from around 2000 to over 6000 feet. The high western Plains of Colorado and Wyoming drop to 2000 feet at the Missouri River Breaks roughly 500 miles to the east. The High Plains extend north from the Platte River for 1500 miles.

Generally the area which makes up the Northern Great Plains were untouched by the Wisconsin glaciations while east of the Missouri River extensive glaciation occurred, the variation in terrain do more to isolate the Northern Great Plains than precipitation does. As the formerly glaciated areas of the northern United States offer more lakes, more forested areas and thus lend themselves to permanent settlement. Lower precipitation, fewer bodies of water, lack of timber and overall continuity of geography were not conducive to permanent settlements before the invention of the steel plow.

The pre-European occupation of the Plains by American Indians was limited for the most part to hunting buffalo, was the primary economic activity. [i] Most tribes lived along streams in semi permanent settlements, such of those that the Corps of Discovery encountered of the Mandan Indians at the present site of Bismarck/Mandan North Dakota. With no means of rapid long-distance overland movement due to no domesticated pack animals other than the with the dog, the Indians could not leave the dependable water supplies of the streams for any long period. This was a substantial problem, for the migration of the buffalo herds often took this food source far away from the settlements for many weeks.

While the Atlantic and Pacific coasts provided ample trade, agricultural and hunting opportunities, as did the lake and river valleys of North and Central America, the Great Plains were largely untenable for settlement beyond the Cheyenne, Missouri and Mississippi river systems. With the discovery and utilization of the horse, the Plains tribes were then much more mobile and capable of hunting the vast buffalo herds. [ii]

Water sources were scarce; often rivers and streams had only a seasonal flow. Those Europeans who arrived early settled along these waterways. The crops that settlers brought with them to the Plains often failed, and crop success varied greatly from year to year as precipitation amounts fluctuated widely. In the later half of the 19^th century, crops that were better adapted to the growing conditions of the region, such as Russian/Ukrainian Hard Red Winter and Spring Wheat were introduced into the agricultural system, and farmers began to improve their understanding of how to use the Plains environment. Thus, for the first 60 plus years of the 19^th century, European settlement of the Northern Great Plains was a rare occurrence and the American Indians of the region were under much less pressure than American Indians were in other regions.

Because of the geographic and settlement realities of the Great Plains, operations and encampments were not as geographically driven as in other regions in North America. On the Great Plains, both northern and southern, there were no places to fortify; very few trails or supply lines to control, in many regards operations on the Great Plains were similar to naval operations or desert warfare in the World Wars.      

During the Wisconsin glaciations the Plesippus species of horse ancestors died out in the Americas, as a result the peoples living in the Americas prior to the European settlement had no large pack animals outside of the Andes Mountain peoples who used the Alpaca and Llama. Escaped Spanish horses from 1520 on created large herds of wild horses, known as mustangs or mestengo. American Indians quickly adopted the horse as a primary means of transportation. [iii] The horse replaced the dog as a travois puller and greatly improved success in battles, trade, and hunts, particularly buffalo hunts. American Indians of the Southwest and western North America, particularly the Nez Perce, developed the first truly American breeds of horse from the escaped or abandoned Spanish stock, the Appaloosa and the Paint by 1800.

In Eurasia the nomadic steppe peoples needed nearly 1500 years to transition to a horse and bow using horse culture, [iv] however in the Americas the transition occurred much more quickly, with the first recorded hunting of buffalo by the Sioux on horseback in the later half of the 17^th century. [v] In North America early contact with trappers [vi] ^{[vii] [viii]} and traders [ix] ^{[x] [xi]} created a gun culture among the American Indians of the Northeast, the Spanish expansion into the Southwest and subsequent withdrawal during the Pueblo revolt [xii] [xiii] had created a horse culture. On the Great Plains these cultures overlapped in the late 18^th century and the last great steppe cavalry culture was created.

North America was, very likely, thinly populated, [xiv] ^[xv] what population centers there were prior to contact with Europeans, were along the Atlantic and Gulf coasts, Ohio valley and Pacific coast. The Great Plains have never been home to large populations following European settlement even with technologies such as irrigation, electricity, and mechanized agriculture. [xvi] The Great Plains Tribes were able to field, at the maximum, 6,000 warriors in the 1870s [xvii] and likely only had 20-30,000 total members. [xviii] Estimates for the population of the Americas prior to European contact and following the colonization of the Americans has been a controversial topic in the last 100 years, with estimates ranging from over one million [xix] to over 100 million. [xx] Hassig estimated the military strength of Mesoamerica alone in 1519-21 to be 25,000 to 43,000 from Tenochtitl‡n, ^[xxi] and another 150,000 to 334,000 from the Valley of Mexico. ^{[xxii] [xxiii]} However, in what would be the United States, a large American Indian community in the 1680s was 6-8,000 people. [xxiv] While in 1866 the United States estimated 270,000 total American Indians in the claimed boundaries of the United States. [xxv] If the total American Indian population had been ten times the 1866 total before pandemics swept the continent from 1750 on for example, 2.7 million American Indians would still be roughly half of the population of the United States 5.3 million from the 1800 Census, [xxvi] and a fraction of the 31.4 million people recorded in the 1860 Census. [xxvii]

Main Indian Tribes of the Great Plains

While there were many tribal groups on the Northern Great Plains, the dominant groups geographically and strategically were the Sioux, Cheyenne, Arapaho, and the Crow. From 1855 on the primary conflict on the Northern Great Plains was that of the Sioux and Cheyenne against the United States Army. For the most part all of the American Indian tribes on the Great Plains shared basic traits, all most all adopted the nomadic horse culture, all hunted the buffalo, and all had strong warrior societies. However similar these groups were, there were variations from tribe to tribe, band to band and between individuals. Due to the nomadic nature of most Plains tribes borders were vague to non-existent and ownership of land was largely non-conceptualized. This is in contrast to the sedentary tribal groups along the Pacific coast, or the agricultural and hunting based groups of the southwest, southeast, and Ohio Valley regions. Some static agricultural groups did live in the Great Plains along the year-round rivers such as the Hidatsa-Mandan-Arikara [xxviii] , and the Ponca, Omaha, Iowa, Osage, Kansas, [xxix] but these groups were smaller and largely settled with the United States and were more easily assimilated into the reservation system that would develop. [xxx]

The Plains Indians had no structured military organization, and conflicts were for the most part low intensity affairs that were largely centered around raids between tribes and smaller groups such as the Ospaye or Tiospayes. During the majority of the year, a Plains Indian tribe were broken up and scattered across a large area in small hunting bands. For example, the Oglala Sioux were organized into twenty-six hunting bands known as Tiospayes. [xxxi] ^[xxxii] A Tiospaye was a self-contained band of 20-30 families that were small enough to operate on its own safely while being able to forage without overtaxing the area in which they operated in. A typical Tiospaye comprised of a man, his brothers along with male cousins and their families who traveled together year-round. Together, each Tiospaye numbered around 150-300 people.

Only the summer did an entire tribe come together for religious ceremonies and larger group hunts. Furthermore, each Tiospaye and Ospaye had a Chief and no Chief had official authority over another Tiospaye or Ospaye. The Cheyenne for example, had a council of 44 Chiefs, know as the Council of Forty-Four of the Cheyenne, with 40 chiefs from the ten Cheyenne bands and four elder or "Old Man Chiefs" who met in the summer on issues that effected all the Cheyenne. [xxxiii] Warfare was generally between Tiospaye or Ospaye sized groups of different tribal groups, for example in 1778, the Lakota were attacked by the Ponca, likely in eastern Dakota or Nebraska, and in the retaliation, the Lakota killed 60 Ponca. [xxxiv]

The Sioux

The dominant tribal group in eastern Wyoming and what would become the Dakota Territory were the Sioux. The term describes any of three divisions of seven tribes who spoke the same language and had cultural similarities but whom often divided into three groups based on their geographic distribution. The Seven Council Fires; also referred to as the Great Sioux Nation are the Mdewakanton, Wahpeton, Wahpekute, Sisseton, Yankton, Yanktonai, and Teton, speaking four distinct dialects of the Sioux language, including the Lakota/Teton, Assiniboine, Santee, and Nakota/Yankton-Yanktonai. [xxxv]

In the 19^th century, the Western groups, called the Lakota or Teton Sioux, were represented by several bands, the Oglala Sioux, the Brule Sioux, the Hunkpapa Sioux, and the Miniconjou Sioux. The Lakota name for "the Nation" is Oceti Sakowin, meaning "Seven Council Fires".

• Santee (Dakota) are the easternmost Sioux group, comprising the first four council fires, and situated between the forks of the Mississippi and Missouri Rivers. [xxxvi]
• Nakota (Yankton-Yanktonai) are the smallest division who migrated west from Minnesota to the area between the Missouri and James Rivers. [xxxvii]
• Lakota (Teton) are the largest group of Sioux and further divided into seven bands: Oglala, BrulŽ, Minniconjou, Sans Arcs, Oohenopa, Sihasapa, and Hunkpapa. [xxxviii]

Santee (Dakota)

The Santee people migrated north and westward from the south and east into Ohio then to Minnesota. The Santee were a woodland people who thrived on hunting, fishing, and subsistence farming. Migrations of Anishinaabe/Chippewa people from the east in the 17th and 18th centuries, with rifles supplied by the French and English, pushed the Santee further into Minnesota, west, and southward. The Santee were involved with the 1862 uprising in Minnesota that is known as the Great Sioux Uprising. [xxxix] [xl]

Yankton-Yanktonai (Nakota)

The Yankton-Yanktonai is a branch of Sioux peoples who moved into northern Minnesota. They originally constituted two main tribes: the Yankton and Yanktonai. Economically, they were involved in quarrying pipestone in Southwestern Minnesota. During the Sioux Uprising in the early 1860s, pressure from the Santee and Europeans forced the Nakota further west into the Dakota Territory.

Lakota (Teton)

The Lakota are closely related to the western Dakota of Minnesota. After their adoption of the horse in the early 18th century, the Lakota became part of the Great Plains culture. By about 1750, the Lakota had moved to the east bank of the Missouri. The large and powerful Omaha, [xli] Pawnee, [xlii] [xliii] Ree, [xliv] Arikara, [xlv] Mandan, [xlvi] and Hidatsa [xlvii] villages had prevented the Lakota from crossing the Missouri for an extended period, [xlviii] but when smallpox and other diseases nearly destroyed these tribes, [xlix] the way was open for the first Lakota to cross the Missouri into the drier, short-grass prairies of the High Plains. [l]

In 1775, an exploring and raiding party led by Chief Standing Bull discovered the Black Hills (Paha Sapa). [li] Around 1775, the Oglala and BrulŽ had also crossed the river, following the great smallpox epidemic of 1772-1780, which destroyed 3/4 of the population of the Missouri Valley populations. [lii] ^[liii] Throughout the late 1770s and through the 1780s the Lakota engaged in warfare with the Ponka, [liv] Mandan, [lv] ^[lvi] Pawnee, [lvii] and Crow [lviii] while gaining control of the land that became the center of the Lakota hunting grounds. Initial contacts between the Lakota and the United States, during the Lewis and Clark Expedition of 1804-06, as well as were the contacts between the Lakota and traders and trappers [lix] were friendly.

However, as more and more settlers crossed Lakota lands, this changed. In Nebraska on September 3, 1855, 700 soldiers under American General William S. Harney avenged the Grattan Massacre [lx] ^[lxi] by attacking a Lakota village, killing 100 men, women, and children. [lxii] Other conflicts with the United States followed; and in 1862-1864, as refugees from the Sioux Uprising in Minnesota fled west to their allies in Montana and Dakota Territory, the war followed them. However, even as the Santee fought the United States in Minnesota, other conflicts occurred between Plains Indian tribes, a pattern that began before contact with the Europeans, and a pattern that continued all throughout the Plains Indian wars with the United States. [lxiii] ^[lxiv]

The Cheyenne

The Cheyenne were originally from what is now northern Minnesota; they had migrated to the high plains by the early 1800's and ranged from the Missouri River in the North to the Arkansas River in the South. They were divided into two branches, the Northern Cheyenne and the Southern Cheyenne. The Northern Cheyenne group spent much of their time on the high plains of Colorado and Wyoming, like the Sioux, with whom they were often allied, the Cheyenne were horsemen and buffalo-hunters who obtained most of their physical needs from the buffalo. In addition, like the Sioux, they celebrated the Summer Sun Dance.

The earliest known official record of the Cheyenne occurred during the mid 17^th century. A group of Cheyenne had visited Fort Crevecoeur, near present-day Chicago. [lxv] During the 1600 and 1700's, the Cheyenne moved from the Great Lakes region to present day Minnesota and North Dakota and established villages. The most prominent of these ancient villages is Biesterfeldt Village, in eastern North Dakota along the Sheyenne River. The Cheyenne also encountered the neighboring Mandan, Hidatsa, and Arikara nations and adopted many cultural characteristics of these peoples. Pressure from migrating Lakota and Ojibwa nations was forcing the Cheyenne to move further west. By the mid 1800's, the Cheyenne had largely abandoned their sedentary, agricultural and pottery traditions and fully adopted the classic nomadic Plains culture. Tipis replaced earth lodges, and the main diet switched from fish and agricultural produce to mainly bison and wild fruits and vegetables. During this time, the Cheyenne also moved into Wyoming, Colorado and South Dakota. [lxvi]

The Arapaho

The Arapaho, although a distinct tribe, were very similar to their close allies, the Cheyenne. Like the Cheyenne, they spoke an Algonquin language and were originally from what is now northern Minnesota. They migrated westward and divided into Northern and Southern branches. The Northern branches lived on the high plains and were more relevant to the historical events played out at Fort Laramie. The Arapaho were mounted bison-hunters who depended on the buffalo for much of their livelihood. They also celebrated the Sun Dance. Blackfoot and Cheyenne are the other Algonquian languages on the Plains, but are quite different from Arapaho. By the 1850s, Arapaho bands separated into two tribes: the Northern Arapaho and Southern Arapaho. The Northern Arapaho Nation has lived since 1878 Wyoming on the Wind River Reservation, the third largest reservation in he United States. The Southern Arapaho Tribe lives with the Southern Cheyenne in Oklahoma.

The Crow

The Crow, also called the Absaroka or Aps‡alooke, are a tribe of Native Americans who historically lived in the Yellowstone river valley and now live on a reservation south of Billings, Montana. The tribal headquarters are located at Crow Agency, Montana. The Crow language is a member of the Missouri Valley Siouan languages. They split from the Hidatsa tribe in present-day North Dakota sometime between 900 to 1500. [lxvii] The Crow are unique to the region in that they are a matrilineal, matrilocal, and matriarchal tribe. The Crow are also unique of the major Plains Indian tribes of the region to have settled quickly and easily with the United States and along with the Hidatsa-Mandan-Arrikira, would provide large numbers of soldiers and scouts to the United States Army throughout the Plains Indian Wars. [lxviii]

European vs. Indian Nation warfare from 1731 through 1860

Initially conflict on the Great Plains was largely conducted on the Southern Great Plains in Spanish Texas that later would become New Mexico, Arizona, and Texas. [lxix] Spanish conflicts began around 1731 and continued through 1790 against the Plains Apaches. As Americas began to move into Texas following the independence of Mexico, they to came into contact and conflict with the Plains Indians already in the region, such as the Plains Apache, Comanche, Jicarilla Apaches, Kiowa, Tonkawa, and Wichita. [lxx] Due to the geographic realities of the Northern Great Plains, there is very little contact and conflict until the Fort Laramie fight on 15 June 1853 [lxxi] and the Grattan Massacre at Torrington Wyoming on 19 August 1854 [lxxii] that began the Sioux War of 1854-'57. Considering the first encounters with Europeans in the later half of the 17^th century [lxxiii] through the Lewis and Clark expedition and years of migration across the Northern Great Plains by Europeans, the Northern Great Plains had a long period of peace between the American Indians and Europeans.

The First Sioux War began with the killing of Grattan's command in August of 1854 and continued through 1856 with engagements at Bluewater Creek Nebraska in which 86 Brul? and 7 solders were killed, [lxxiv] and raids and retaliation against emigrants, American settlements and stagecoaches. [lxxv] While the First Sioux War did lead to many deaths, it was a very low intensity conflict driven largely from the destruction of a Platoon-equivalent from G Company, 6^th Infantry. Other larger scale conflicts were occurring in California, Oregon and on the Southern Great Plains. [lxxvi]

For all intents and purposes, warfare on the Northern Great Plains from 1803 through 1860 was a very low intensity conflict between Europeans and the Plains Indians, with one breakout that lead to less than one thousand dead on both sides. [lxxvii] The power vacuum caused by the Civil War would lead to a much longer and more violent series of wars on the Northern Great Plains.

Shift in tactics and the Civil War

While the fighting between the United States and Kaw, Comanches, Kiowa drifted into the Northern Great Plains at Republican Fork in Nebraska, [lxxviii] the Northern Great Plains generally was calm following the First Sioux War, as long as the United States abided by the Fort Laramie Treaty of 1851 the Plains Indians remained peaceful. [lxxix] ^[lxxx] During the succession crisis of 1860-'61 the Army split into Unionist and Confederate loyalties and the majority of Regular and Militia units were called back to the east, as were many men of fighting age. The fighting continued in the Southwest, California, Oregon, and Idaho [lxxxi] while the Northern Great Plains remained quiet until the summer of 1862.

In 1851, the U.S. and Santee had negotiated the Treaty of Traverse des Sioux and Treaty of Mendota [lxxxii] , ceding vast amounts of land in Minnesota Territory. In exchange for money and goods, the Dakota agreed to live on a twenty-mile wide reservation centered on a 150-mile stretch of the upper Minnesota River. [lxxxiii] The situation was not resolved as the United States Senate deleted Article 3 of each treaty during the ratification process. Much of the promised compensation never arrived, lost or effectively stolen due to corruption.

As Minnesota became a state in 1858, representatives of several Dakota bands led by Chief Little Crow traveled to Washington, D.C. to make further negotiations. Again, events did not transpire in the Indians' favor. The northern half of the reservation along the Minnesota River was lost, and rights to the quarry at Pipestone, Minnesota were ceded. [lxxxiv] This was a major blow to the standing of Little Crow in the Dakota community. In the summer of 1862, relations between the whites and Plains Indians degraded because of unpaid annuities, unscrupulous traders, poor diplomacy, and summer heat in Southwestern Minnesota. On 17 August 1862 4 Santee hunters killed white settlers near Acton Minnesota. [lxxxv] Other Sioux from a number of Santee bands decided open warfare against the whites was a good idea and so the next day there would be war under the leadership of Little Crow. [lxxxvi]

On August 18, 1862, the Sioux opened their war with raids on Redwood Agency and roughly 200 settlers in Renville County along the Minnesota River [lxxxvii] . Captain John Marsh with the 5^th Minnesota Infantry to the Lower Sioux Ferry, 34 died including the Captain during an ambush. [lxxxviii] On 19 and 23 August New Ulm Minnesota was attacked by the Mdewakanton Santee under Little Crow, the settlers and refugees organized a militia and held New Ulm during a number of attacks, losing 32 dead while over 100 Santee died, over 190 buildings in the area were burned. [lxxxix] On August 20, 400 Santee under Little Crow attacked Fort Ridgely's 180 soldiers and 250 refugees; the attack was repulsed by canister shot from old howitzers. [xc] On 22 August, Little Crow assaulted the Fort with over 800 warriors, again the howitzers allowed the whites to keep the Fort, in all 5 soldiers were killed, and at least 100 Santee graves in the woods. [xci]

On the night of 2/3 September a detachment from relief force of the 6^th Minnesota Infantry that was recovering bodies and relieving the soldiers and civilians at New Ulm and Fort Ridgley was attacked at Birch Coulee near Morton Minnesota. 24 whites were killed, 67 wounded while only 2 Santee were killed. [xcii] Further attacks at Hutchinson Minnesota and Fort Abercrombie (Fargo) Dakota Territory were repulsed with few casualties to either side. [xciii]

By the end of September Colonel Sibley lead a large force of 1,619 combatants [xciv] against the Santee which lead to fighting on 23 September 1862 at Wood Lake. Many Santee did not join in the attacks, choosing to aid and protect settlers and to serve with the Minnesota soldiers who responded to the attacks. The Yankton Sioux chief Struck by the Ree deployed his warriors for this purpose. The fight at Wood Lake broke the will of the Santee when over 25 warriors were killed along with Chief Mankato, Little Crow fled into the Dakota Territory with around 200 warriors while 2000 Santee surrendered. [xcv]

The Sioux Uprising ended with hundreds of dead settlers and half-breeds and over one hundred soldiers killed and likely hundreds of Sioux warriors dead. 303 Sioux prisoners were convicted of murder and rape by military tribunals and sentenced to death six weeks after the uprising ended. President Lincoln reviewed the trial records and distinguished between those who had engaged in warfare against the United States and those who had committed the crimes of rape or murder of civilians. He approved of the execution of 38 and commuted the death sentences of the others, largely due to the pleas from Bishop Henry Whipple for clemency. [xcvi] The 38, for whom the evidence seemed strongest, were executed by hanging in a single day on December 26, 1862 in Mankato Minnesota. Little Crow was killed while on a horse-stealing expedition, a 17 man band of Santee entered the Big Wood region of Minnesota, some of the Santee broke off and at Howard Lake the struck the Dustin family, killing four. [xcvii] On 3 July 1863, Little Crow was killed by a settler while foraging at Hutchinson Minnesota. [xcviii]

The retaliation for the Sioux Uprising continued into 1863 with 3,220 men, the largest force assembled in the western Indian Wars, when Sibley lead this force in a sweep to clear Minnesota and the eastern Dakota territory of hostile American Indians. At Big Mound in the Dakota Territory Sibley engaged the Sisseton and Wahpeton Sioux on 24 July 1863, killing 40 Sioux while losing 4. [xcix] Throughout the remainder of 1863 and into 1864, Sibley maneuvered and fought the Sioux, in the style all the previous Indian conflicts in the American West, maneuver, find the enemy, engage, and withdraw to find more combatants in hopes of getting a settlement. Meanwhile in Colorado and northern Dakota, a new form of Indian War developed at Sand Creek and Killdeer Mountain.

During the winter of 1863–1864, Sully's superior, Major General John Pope, formulated a plan for ending the war with the Sioux. He would order a large force of infantry, cavalry, scouts, mounted infantry and a large support train along with howitzers, [c] commanded by Sully, into the field to find the Sioux and engage them in battle. In addition, he would send infantry behind Sully's force to establish strong-posts in the "Indian country." They established Fort Rice on 7 July at the mouth of Cannonball River and moved on. The Sioux, who had been operating north of Fort Rice, moved across the Missouri River and took a strong position on the Little Missouri River, about 200 miles from the fort. On 26 July, Sully marched out to engage them in battle. On the 28th, he arrived near the Sioux camp that he reported included 3,000-5,000 warriors lead by Sitting Bull and Gall dug in around a larger 1,600-lodge camp. [ci] Heavy fighting ensued, but eventually the artillery and long-range firearms took effect and the Sioux began losing ground. The camp was taken with heavy artillery fire and the civilians and warrior broke and fled. Over 150 warriors were killed; 40 tons of pemmican, and hundreds of tipis burned, and over 3,000 dogs were killed for the loss of 5 soldiers. [cii] On 7-9 August Sully crossed the North Dakota Badlands and was attacked at the Little Missouri River by survivors of Killdeer Mountain, over one hundred Sioux were killed for the loss of 9 Union soldiers.

While not technically part of the Northern Great Plains theatre, the events at Sand Creek in November 1864 created the environment under which Northern Great Plains tribes operated. While Sully's campaign could have killed many more civilians than Chivington's assault did, Sully, like Sherman, was able to restrain his soldiers and focus their violence against the Sioux warriors, and only once the civilians fled did they destroy the camp at Killdeer Mountain. Chivington also led an assault in retaliation for an attack on settlers, in this case due to Hungate Massacre on 11 June 1864. Chivington, unlike Sully planned to kill any Cheyenne his command came across, warrior, civilian, peaceful, or hostile.

Many of the Southern Cheyennes and Arapahos were ready for peace and camped near Fort Lyon on the eastern plains. Both of the tribes had recently signed a treaty with the United States in which they ceded their lands to the United States and agreed to move to the Indian reservation to the south of Sand Creek in Oklahoma. [ciii] Black Kettle, one chief of a group of mostly Southern Cheyennes and some Arapahos, some 800 in number, reported to Fort Lyon in an effort to declare peace.

Colonel John Chivington and his 800 troops of the 1^st  Colorado Cavalry, 3^rd Colorado Cavalry and a company of 1^st New Mexico Volunteers marched to their campsite in order to attack the Indians. On the morning of November 29, 1864, the army attacked the village of 115 Cheyenne and 8 Arapaho lodges and massacred most of its inhabitants. Fifteen soldiers were killed and over 50 wounded [civ] , making Sand Creek one of the most costly battles in the Plains Indian wars. Between 120 and 184 Cheyennes were reported dead, and some were reportedly mutilated, and most were women, children, and elderly men. Chivington and his men later displayed scalp and other body parts in the Apollo Theater in Denver. [cv] While historically called a massacre, the number of soldiers killed and wounded indicates it was a hard fight for the soldiers, even against civilians.

While Sully and Sibley's campaigns in Minnesota and the northern half of the Dakota territory were able to break the back of Sioux resistance and settle the regions in regards to further uprisings without overt assaults on non-combatants, Chivington's assault was a military failure in terms of Unions soldiers killed, as many as died in both of Sully's fights. Furthermore, it failed strategically since the Northern and Southern Cheyenne as well as Lakota rose up across Colorado, Nebraska, Wyoming, and the Dakota in retaliation for Sand Creek from 1865 through 1868.