President Lincoln's 75,000 volunteers

Events leading to the American Civil War
  1. Northwest Ordinance
  2. Kentucky and Virginia Resolutions
  3. End of Atlantic slave trade
  4. Missouri Compromise
  5. Tariff of 1828
  6. Nat Turner's Rebellion
  7. Nullification crisis
  8. End of slavery in British colonies
  9. Texas Revolution
  10. United States v. Crandall
  11. Gag rule
  12. Commonwealth v. Aves
  13. Murder of Elijah Lovejoy
  14. Burning of Pennsylvania Hall
  15. American Slavery As It Is
  16. United States v. The Amistad
  17. Prigg v. Pennsylvania
  18. Texas annexation
  19. Mexican–American War
  20. Wilmot Proviso
  21. Nashville Convention
  22. Compromise of 1850
  23. Uncle Tom's Cabin
  24. Recapture of Anthony Burns
  25. Kansas–Nebraska Act
  26. Ostend Manifesto
  27. Bleeding Kansas
  28. Caning of Charles Sumner
  29. Dred Scott v. Sandford
  30. The Impending Crisis of the South
  31. Panic of 1857
  32. Lincoln–Douglas debates
  33. Oberlin–Wellington Rescue
  34. John Brown's raid on Harpers Ferry
  35. Virginia v. John Brown
  36. 1860 presidential election
  37. Crittenden Compromise
  38. Secession of Southern states
  39. Peace Conference of 1861
  40. Corwin Amendment
  41. Battle of Fort Sumter

On April 15, 1861, at the start of the American Civil War, U.S. President Abraham Lincoln called for a 75,000-man militia to serve for three months following the bombardment and surrender of Fort Sumter. Some southern states refused to send troops against the neighboring Deep South slave states of South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas. The result was that most states in the Upper South of Virginia, Arkansas, North Carolina, and Tennessee also declared secession from the United States and joined the Confederate States.

In Missouri and Kentucky, pro-Confederate state governments were formed. Although neither managed to seize effective control, they were duly recognized by the Confederacy with these states being admitted as the 12th and 13th Confederate states, respectively. Meanwhile, movement towards secession was forcibly suppressed by Federal troops in Maryland and not attempted in Delaware, with both states staying in the Union throughout the duration of the war.