| 1860 | |
| December 20 | South Carolina becomes the first state to secede from the United States. |
| 1861 | |
| February 1 | Texas secedes. |
| February 4 | The Confederacy is formed and begins a constitutional convention in Montgomery, Alabama. The first states to join the Confederacy are North and South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and Texas. |
| February 7 | Choctaw Nation affirms amity with the Confederacy. |
| February 17 | Inter-tribal council called to discuss the relations that the Five Civilized Tribes will have with the United States and the Confederacy. |
| April 12 | Confederate forces fire on Fort Sumter. |
| April 15 | President Lincoln declares a state of insurrection and sends out a call for volunteers. |
| May 4 | United States withdraws army garrisons in Indian Territory posts. |
| May 6 | Arkansas secedes. |
| May 25 | Chickasaw Nation declares independence and allies with the Confederacy. |
| June 14 | Choctaw Nation declares its independence, allies with the Confederacy, and authorizes formation of a regiment. |
| July 12 | Stand Watie raises a private Cherokee battalion of Mounted Rifles for the Confederacy. |
| July 24 | 1st Choctaw and Chickasaw Mounted Rifle Regiment completes mustering. |
| August 1 | Seminole Nation joins the Confederacy. |
| August 10 | Battle of Wilson’s Creek. Watie’s 1st Cherokee Volunteers participate on Confederate side. |
| August 17 | Creek Mounted Rifle regiments are organized by the pro-Confederate faction of the Creek Nation. |
| August 26 | Cherokee Nation declares war on the United States. |
| September 19 | Seminole Mounted Rifle battalion organized. |
| October 4 | A Cherokee regiment (Drew’s Mounted Rifles) raised. Many members are Union loyalists. |
| November 15 | Loyal Creeks and Seminoles led by Opothleyohola begin retreat to Kansas. |
| November 19 | Battle of Round Mountain. Confederates attack the pro-Union Creek and Seminole Indians. |
| December 9 | Battle of Chusto-talasah (or Bird Creek). |
| December 26 | Battle of Chustenahalan – loyalist Indians driven from Indian Territory. |
| 1862 | |
| March 7–8 | Battle of Pea Ridge – Indian regiments participate. |
| April 4 | 1st and 2nd Indian Home Guard Regiments (USA) authorized. |
| June 21 | First Indian Expedition begins. Union forces enter Cherokee Nation from Fort Scott. |
| July 14 | Union forces capture Tahlequah, the Cherokee capital. |
| July 16 | The Cherokee Nation declares for the Union, then splits into Union and Confederate factions. Drew’s Mounted Rifles (CSA) deserts and is later reorganized as the 3rd Indian Home Guard Regiment (USA). |
| July 18 | Union captures Fort Gibson. |
| July 19 | White Union troops evacuate the Cherokee Nation. |
| July 28 | After the withdrawal of white Union troops, Indian Home Guard regiments are forced to retreat back to Kansas. First Indian Expedition ends. |
| October 10 | Second Indian Expedition begins. |
| October 22 | Battle of Old Fort Wayne, at Beattie’s Prairie, Indian Territory. |
| October 23 | Pro-Union Indians at the Wichita Agency revolt against the Confederacy and flee to Kansas. |
| October 30 | Battle of Newtonia. Indian units participate on both sides. |
| December | Union Indians capture Forts Gibson and Davis from Confederate forces. Fort Davis destroyed by Union. |
| 1863 | |
| February 3 | Northern Cherokees emancipate Negro slaves owned by Cherokees. |
| May | Union reoccupies Fort Gibson and holds it for the rest of the war. |
| July 1–2 | Battle of Cabin Creek. Union victory secures Fort Gibson’s supply line. |
| July 4 | Gettysburg ends and Vicksburg surrenders. |
| July 17 | Battle of Honey Springs seriously weakens Confederates. |
| August 21 | Quantrill sacks Lawrence, Kansas. |
| September 1 | Union forces occupy Fort Smith, Arkansas. |
| October 6 | Battle of Baxter Springs cuts supply lines to Fort Gibson. |
| December 16 | Quantrill’s attack on Fort Gibson repulsed. |
| 1864 | |
| February 15 | Battle of Middle Boggy Depot. |
| April 18 | Battle of Poison Springs, Arkansas. Chickasaw and Choctaw regiments participate. |
| June 15 | Steamboat J.R.Williams captured by Confederate Indians while carrying supplies to Fort Gibson. |
| August 22 | Atlanta falls. |
| September 19 | 2nd battle of Cabin Creek. Union supply train captured. |
| November 8 | Lincoln reelected. |
| 1865 | |
| April 3 | Richmond falls to the Union. |
| April 9 | Lee surrenders at Appomattox. |
| May 26 | Kirby-Smith sends Confederate troops right into the Trans-Mississippi. |
| June 18 | Choctaw Nation ceases hostilities. |
| June 23 | Stand Watie surrenders his command. Cherokee, Creek, and Seminole Nations cease hostilities. |
| July 16 | Chickasaw Nation ceases hostilities. |
| 1866 | |
| April 28 | Choctaw and Cherokee Nations sign peace treaties with the United States. |
| July 19 | Cherokee Nation signs a peace treaty with the United States. |
Black Beaver, a Delaware, served as a scout in the United States Army during both the Mexican–American War and the Civil War. During the Civil War, he guided Union garrisons out of the Indian Territory at the beginning of the war. Chased out of his home in Fort Washita for his Union sympathies, he fought for the North during the rest of the war. (NARA)
Indian Territory during the Civil War.