- November 6: Abraham Lincoln wins the 1860 presidential election on a platform that includes the prohibition of slavery in new states and territories. Lincoln wins all of the electoral votes in all of the free states except New Jersey, where he wins 4 votes and Stephen A. Douglas wins 3. The official count of electoral votes occurs February 13, 1861.
- November 7: Charleston, South Carolina authorities arrest a Federal officer who had attempted to move supplies to Fort Moultrie from Charleston Arsenal. Two days later, the Palmetto Flag of South Carolina is raised over the Charleston harbor batteries.
- November 9: A false report that U.S. Senator Robert Toombs of Georgia has resigned reaches Columbia, South Carolina.
- November 10: The South Carolina legislature calls for an election on December 6 for delegates to a convention for December 17 to consider whether the State should secede from the Union. U.S. Senators James Chesnut, Jr. and James Henry Hammond of South Carolina resign from the U.S. Senate.
- November 14:
- Congressman Alexander H. Stephens of Georgia, later Vice President of the Confederate States of America, speaks to the Georgia legislature in opposition to secession.
- The Governor of Alabama says he will call for an election on December 6 or December 24 for delegates to a convention to meet on January 7 to consider whether the State should secede from the Union.
- The Governor of Mississippi calls for an extraordinary session of the legislature on November 26. On November 29, the legislature votes for an election on December 29 for delegates to a convention to meet on January 7 to consider whether the State should secede from the Union.
- November 15:
- November 18:
- The Georgia legislature voted on November 18 for an election on January 2 for delegates to a convention to meet on January 16 to consider whether the State should secede from the Union.
- The Florida legislature voted to call a convention.
- November 20: Lincoln says that his administration will permit states to control their own internal affairs.
- November 22: The Governor of Louisiana calls a special session of the legislature for December 10.
- November 23: Major Anderson requests reinforcements for his small force at Charleston.
- December 4: President Buchanan condemns Northern interference with slave policies of Southern states but also says states have no right to secede from the Union. The U.S. House of Representatives appoints a Committee of Thirty-Three to consider "the present perilous condition of the country".
- December 8, 1860 – January 8, 1861: Buchanan administration cabinet members from the South resign. Secretary of the Treasury Howell Cobb of Georgia resigns on December 8. On December 23, President Buchanan asks for the resignation of Secretary of War John B. Floyd, a former governor of Virginia, whose actions appear to favor the Southern secessionists. He arranged to shift weapons from Pittsburgh and other locations to the South. Floyd resigns on December 29. The War Department stops the transfer of weapons from Pittsburgh on January 3. United States Secretary of the Interior Jacob Thompson of Mississippi resigns on January 8, 1861.
- December 10: South Carolina delegates meet with Buchanan and believe he agrees not to change the military situation at Charleston.
- December 11: Major Don Carlos Buell delivers a message to Major Anderson from Secretary of War Floyd. Anderson is authorized to put his command in any of the forts at Charleston to resist their seizure. Later in the month Floyd says Anderson violated the President's pledge to keep the status quo pending further discussions and the garrison should be removed from Charleston. Floyd soon will join the Confederacy.
- December 12: Secretary of State Lewis Cass of Michigan resigns. He believes President Buchanan should reinforce the Charleston forts and is unhappy about Buchanan's lack of action.
- December 17, 20, 24: The South Carolina Secession Convention begins on December 17. On December 20, secession begins when the convention declares "that the Union now subsisting between South Carolina and other states under the name of the 'United States of America' is hereby dissolved". The convention published a Declaration of the Immediate Causes Which Induce and Justify the Secession of South Carolina from the Federal Union in explanation and support of their position. The document cites "encroachments on the reserved rights of the states" and "an increasing hostility of the non-slaveholding states to the institution of slavery" and "the election of a man to the high office of President of the United States, whose opinions and purposes are hostile to slavery" as among the causes. On December 24, South Carolina Governor Francis Wilkinson Pickens declares the act of secession in effect.
- December 18, 1860 – January 15, 1861: Senator John J. Crittenden of Kentucky proposes the "Crittenden Compromise". Its main features are a constitutional amendment that would reinstate the Missouri Compromise line between free and slave territory and retention of the fugitive slave law and slavery where it existed, including in the District of Columbia. On January 16, 1861, the Crittenden Compromise is effectively defeated in the United States Senate.
- December 20: Vice President John C. Breckenridge of Kentucky, unsuccessful candidate of the Southern Democrats for President and later Confederate general and Confederate Secretary of War, appoints a Committee of Thirteen U.S. Senators of differing views, including Jefferson Davis, Robert Toombs, William Seward, and Stephen A. Douglas, to consider the state of the nation and to propose solutions to the crisis. On December 31, the Committee reports they are unable to agree on a compromise proposal.
- December 21, 24: The four United States Congressmen from South Carolina withdraw from the U.S. House of Representatives, but on December 24 the House refuses their resignations.
- December 26–27, 30: Under cover of darkness, Major Anderson moves the Federal garrison at Charleston, South Carolina from Fort Moultrie, which is indefensible from the landward side, to the unfinished Fort Sumter, which is located on an island in Charleston harbor. He spikes the guns of Fort Moultrie. Secessionists react angrily and feel betrayed because they thought President Buchanan would maintain the status quo. The next day South Carolina troops occupy the abandoned Fort Moultrie and another fortification, Castle Pinckney, which had been occupied only by an ordnance sergeant. On December 30, South Carolina troops seize the Charleston Arsenal.
- December 28: Buchanan meets with South Carolina commissioners as "private gentlemen". They demand removal of federal troops from Charleston. Buchanan states he needs more time to consider the situation. On December 31, Buchanan says Congress must define the relations between the Federal government and South Carolina and that he will not withdraw the troops from Charleston.
- December 30, 1860 – March 28, 1861: Brevet Lieutenant General Winfield Scott, general-in-chief of the U.S. Army, asks permission from President Buchanan to reinforce and resupply Fort Sumter but receives no reply. On March 3, 1861, Scott will tell Secretary of State–designate William Seward that Fort Sumter can not be relieved. On March 5, he will tell President Lincoln that he agrees with Major Anderson's assessment that the situation at Charleston could only be saved for the Union with 20,000 reinforcements. On March 6, Scott says the U.S. Army can do no more to relieve Fort Sumter and only the U.S. Navy could aid the fort's garrison. On March 11, he again advises President Lincoln that it would take many months for the army to be able to reinforce Fort Sumter. On March 28, Scott recommends to the President that Fort Sumter and Fort Pickens at Pensacola, Florida be evacuated.
- December 31: The South Carolina convention votes for election of commissioners to other Southern states which called conventions to meet to form a provisional government.
- January 2:
- South Carolina troops take control of dormant Fort Jackson in Charleston harbor.
- Colonel Charles Stone begins to organize the District of Columbia militia.
- January 3:
- South Carolina commissioners propose a meeting to form a provisional government for February 4 in Montgomery, Alabama.
- Delaware legislators reject secession proposals.
- January 3, 24, 26: Georgia state troops take Fort Pulaski at the mouth of the Savannah River on January 3, the United States Arsenal at Augusta, Georgia on January 24, and Oglethorpe Barracks and Fort Jackson at Savannah, Georgia on January 26.
- January 4–5, 30: Alabama seizes the Mount Vernon, Alabama United States Arsenal on January 4, Fort Morgan and Fort Gaines at the entrance to Mobile Bay on January 5, and the U.S. Revenue Cutter Lewis Cass at Mobile, Alabama on January 30.
- January 5:
- The unarmed merchant vessel Star of the West, which is under contract to the War Department, heads for Fort Sumter from New York with 250 reinforcements and supplies.
- U.S. Senators from seven deep South states meet and advise their states to secede.
- January 6–12: Florida troops seize Apalachicola, Florida Arsenal on January 6 and Fort Marion at Saint Augustine on January 7. On January 8, Federal troops at Fort Barrancas or Barrancas Barracks at Pensacola, Florida fire on about 20 men who approach the fort at night. The men flee. After the Federal troops move from Fort Barrancas to Fort Pickens on Santa Rosa Island, Florida in Pensacola Harbor on January 10, Florida forces seize Barrancas Barracks, Fort McRee, and the Pensacola Navy Yard on January 12.
- January 8: Irregularly arranged voting for a Texas convention begins after Governor Sam Houston refused to call a session of the legislature.
- January 9:
- January 10: Florida secedes from the Union.
- January–February: Louisiana state troops seize the United States Arsenal and Barracks at Baton Rouge and Fort Jackson and Fort St. Philip near the mouth of the Mississippi River on January 10, the United States Marine Hospital south of New Orleans on January 11, Fort Pike, near New Orleans, on January 14, Fort Macomb, near New Orleans, on January 28, the U. S. Revenue Cutter Robert McClelland at New Orleans on January 29, the United States Branch Mint and Customs House at New Orleans and the U.S. Revenue Schooner Washington on January 31, and the U.S. Paymaster's office at New Orleans on February 19.
- January 11: Alabama secedes.
- January 12: Mississippi representatives to the U.S. Congress resign.
- January 14, 18: Federal troops occupy Fort Taylor at Key West, Florida. This became an important base of supply, including coal, for blockaders and other vessels on January 14. A U.S. force also garrisons Fort Jefferson on the Dry Tortugas, Florida on January 18.
- January 19: Georgia secedes from the Union.
- January 20: Mississippi troops seize Fort Massachusetts and other installations on Ship Island in the Gulf of Mexico.
- January 21: U.S. Senators Clement C. Clay, Jr. and Benjamin Fitzpatrick from Alabama, David L. Yulee and Stephen R. Mallory from Florida, and Jefferson Davis from Mississippi withdraw from the U.S. Senate.
- January 26: Louisiana secedes from the Union.
- January 29: Kansas is admitted to the Union. The 34th state is a free state under the Wyandotte Constitution.
- February 1: The Texas convention approves secession but provides for a popular vote on February 23. On February 11, the Texas convention approves formation of a Southern Confederacy. Seven Texas delegates to the Montgomery convention are elected. On February 23, Texans vote for secession by a 3 to 1 margin.
- February 4:
- Virginians vote for convention delegates, only 32 of 152 are immediate secessionists; the voters require any action by the convention to be submitted to the voters.
- U.S. Senators Judah Benjamin and John Slidell of Louisiana leave the U.S. Senate.
- February 4, 8–10: Secessionists meet in convention in Montgomery, Alabama to provide a government for the seceded States beginning on February 4. They act as the Provisional Congress of the Confederate States of America. On February 8, the convention drafts a Provisional Constitution of the Confederate States. The Confederate States of America (the "Confederacy") is not recognized by the United States government or any foreign government. Border states initially refuse to join Confederacy. On February 9, the convention chooses Jefferson Davis as Provisional President and Alexander Stephens as Provisional Vice President of the Confederate States. On February 10, Davis is surprised to learn of his election as Provisional President of the Confederacy but he accepts the position.
- February 4–27: Peace conference or peace convention called by Virginia meets in Washington. None of the seceded states are represented. Five Northern states also do not attend. On February 27, after much bickering, the convention sends recommendations for six constitutional amendments along the lines of the Crittenden Compromise to Congress and adjourns. The U.S. Senate rejects the Peace Convention proposals on March 2.
- February 5: President Buchanan tells South Carolina commissioners that Fort Sumter will not be surrendered.
- February 7: The Choctaw Nation aligns with the Southern States.
- February 8, 12: Arkansas troops seize the United States Arsenal at Little Rock and force the Federal garrison to withdraw on February 8. They seize the United States ordnance stores at Napoleon, Arkansas on February 12.
- February 9
- Tennessee voters vote against calling a secession convention.
- USS Brooklyn arrives with reinforcements for Fort Pickens but does not land because of a local agreement of both sides not to alter the military situation.
- February 12: The Provisional Confederate Congress chosen by the Montgomery convention approves a Peace Commission to the United States. The group assumes authority to deal with the issue of disputed forts.
- February 13: A Virginia convention meets at Richmond to consider whether Virginia should approve secession.
- February 16: Texas forces seize the United States Arsenal and Barracks at San Antonio.
- February 18:
- U.S. Brigadier General and Brevet Major General David E. Twiggs surrenders U. S. military posts in the Department of Texas to the State of Texas and effectively surrenders the one-fourth of the United States Army which is stationed in Texas. Twiggs tells authorities in Washington he acted under threat of force but they consider his actions to be treason. On March 1, U. S. Secretary of War Joseph Holt orders Brigadier General Twiggs dismissed from the U. S. Army "for his treachery to the flag of his country" in his surrender of military posts and Federal property in Texas to state authorities. Twiggs soon joins the Confederate States Army.
- Arkansas voters elect a majority of Unionists to their convention.
- Missouri voters elect all conditional or unconditional Unionists to their convention.
- Jefferson Davis is inaugurated as President of the Confederacy.
- February 19 – April 13: Colonel Carlos A. Waite at Camp Verde, Texas took over nominal command of U.S. posts in the state but the camps and forts would soon fall to state forces following General Twiggs's surrender on the previous day. Texas forces seize United States property at Brazos Santiago on February 19 and the U.S. Revenue Cutter Henry Dodge at Galveston, Texas on March 2. Federal garrisons abandon Camp Cooper, Texas on February 21, Camp Colorado, Texas on February 26, Ringgold Barracks and Camp Verde, Texas on March 7, Fort McIntosh, Texas on March 12, Camp Wood, Texas on March 15, Camp Hudson, Texas on March 17, Fort Clark, Fort Inge, and Fort Lancaster, Texas on March 19, Fort Brown and Fort Duncan, Texas on March 20, Fort Chadbourne, Texas on March 23, Fort Bliss, Texas on March 31, Fort Quitman, Texas on April 5, and Fort Davis, Texas on April 13.
- February 27: President Davis appoints three commissioners to attempt negotiations between the Confederacy and the Federal government.
- February, March–October: A Missouri State Convention meets in Jefferson City to consider secession. Unionists led by Francis Preston Blair, Jr. prevent secession. The Missouri legislature condemns secession on March 7. On March 9, a Missouri state convention is held in St. Louis and Unionists again thwart secessionists. On March 22, a Missouri convention again rejects secession contrary to the position of pro-Confederate Governor Claiborne Jackson. This will not end the dispute over secession in Missouri. Eventually, on October 31, 1861, under the protection of Confederate troops, secessionist members of the Missouri legislature meeting at Neosho, Missouri adopt a resolution of secession. The Confederate Congress seats Missouri representatives but Missouri remains in the Union and at least twice as many Missouri men fight for the Union as fight for the Confederacy.
- February 28: North Carolina voters reject a call for a state convention to consider secession by 651 votes out of over 93,000.
- February 28: Colorado Territory is organized.
- March 1:
- The Confederate States take over the military at Charleston, South Carolina. Confederate President Davis appoints P. G. T. Beauregard as brigadier general and assigns him to command Confederate forces in the area. Beauregard assumes command of Confederate troops at Charleston on March 3.
- Major Anderson warns Washington authorities that little time remains to make a decision whether to evacuate or reinforce Fort Sumter. Local authorities had been allowing the fort to receive some provisions but Confederates were training and constructing works around Charleston harbor.
- March 2:
- The Provisional Confederate Congress admits Texas to the Confederacy.
- Congress approved by joint resolution a proposed constitutional amendment that would prohibit a further constitutional amendment to permit Congress to abolish or interfere with a domestic institution of a state, including slavery. It is too late to be of practical importance.
- Nevada Territory and Dakota Territory are organized.
- March 4: Abraham Lincoln is inaugurated as 16th President of the United States. He states his intentions not to interfere with slavery where it exists and to preserve the Union.
- March 8, 13: The Confederate commissioners present their terms to avoid war and try to reach Secretary of State Seward through pro-Confederate U.S. Supreme Court Justice John A. Campbell. President Lincoln will not meet with the Confederate commissioners because it would appear to recognize the seceded states were out of the union.
- March 11, 13, 16, 21, 23, 29, April 3, 22: The Confederate Congress adopts a permanent Constitution of the Confederate States on March 11. The then seceded states ratify this constitution on March 13 (Alabama), March 16 (Georgia), March 21 (Louisiana), March 23 (Texas), March 29 (Mississippi), April 3 (South Carolina), and April 22 (Florida).
- March 15: Lincoln asks his Cabinet members for their written advice on how to handle Fort Sumter situation. For various reasons, over the next two weeks, members advise the President not to attempt to relieve Fort Sumter. Seward gives lengthy advice on how to run the government and handle the crisis. On April 1, President Lincoln tactfully apprises Secretary Seward that he, not Seward, is President and rejects Seward's proposal that Lincoln grant him broad powers in foreign affairs and dealing with the Confederacy. Seward becomes a loyal supporter of Lincoln.
- March 16:
- President Davis names three commissioners to Britain; they will not be officially received by the British government.
- Pro-Confederates declare Arizona part of the CSA.
- March 18:
- Governor Sam Houston of Texas refuses to take oath of allegiance to Confederacy and is deposed by the Texas secession convention. Houston said: "You may, after the sacrifice of countless millions of treasures and hundreds of thousands of precious lives, as a bare possibility, win Southern independence...but I doubt it."
- Confederate Brigadier General Braxton Bragg forbids the garrison at Fort Pickens at Pensacola, Florida to receive more supplies.
- March 18: An Arkansas convention rejects secession by four votes but provides for a popular vote on the issue in August.
- March 20: Confederate forces at Mobile, Alabama seize the USS Isabella, which is carrying supplies for Fort Pickens.
- March 21:
- President Lincoln's representative, former naval commander Gustavus Vasa Fox, visits Charleston and Fort Sumter and talks both to Major Anderson and the Confederates. Fox thinks that ships still can relieve the fort.
- Speaking at Savannah, Georgia, Confederate Vice President Alexander H. Stephens acknowledges that black slavery is the "cornerstone" of the Confederate government.
- March 25: Federal Colonel Ward Hill Lamon and Stephen A. Hurlbut confer with Confederate Brigadier General Beauregard and South Carolina Governor Pickens.
- March 29: President Lincoln orders relief expeditions for Fort Sumter and Fort Pickens to be prepared to depart for the forts by April 6. On March 31, he orders the relief expedition to Fort Pickens to proceed.
- April 3:
- President Lincoln sends Allan B. Magruder to Richmond to attempt to arrange talks with Virginia unionists.
- A Confederate battery on Morris Island in Charleston harbor shoots at the American vessel Rhoda H. Shannon.
- April 4:
- A Virginia State Convention rejects a motion to pass an ordinance of session.
- President Lincoln advises Gustavus V. Fox that Fort Sumter will be relieved. He drafts a letter for Secretary of War Cameron to send to Major Anderson.
- April 5: Secretary of the Navy Gideon Welles orders four ships to supply Fort Sumter, but one, USS Powhatan, had already left for Fort Pickens under President Lincoln's previous order.
- April 6:
- President Lincoln informs South Carolina that an attempt will be made to resupply Fort Sumter but only with provisions.
- Since an earlier order was not carried out, orders were sent from Washington to reinforce Fort Pickens with Regular Army troops.
- April 7:
- April 8:
- April 9: The steamer Baltic with Gustavus V. Fox as Lincoln's agent aboard sails from New York for relief of the Charleston garrison.
- April 10: USS Pawnee leaves Norfolk for Fort Sumter.
- April 11: Confederates demand surrender of Fort Sumter. After discussing the matter with his officers, Anderson refuses but mentions the garrison will be starved out in a few days without relief.
- April 12–13: Federal troops land on Santa Rosa Island, Florida and reinforce Fort Pickens. Because of the fort's location, Confederates are unable to prevent the landings. On April 13, U.S. Navy Lieutenant John L. Worden, who had carried the orders to land the reinforcements at Fort Pickens to the U. S. Navy at Pensacola, is arrested by Confederate authorities near Montgomery, Alabama.
- April 12–14: Major Anderson tells Confederate representatives that he must evacuate the fort if not reinforced and resupplied by April 15. The Confederates know relief is coming and has almost arrived so they open fire on the fort at 4:30 a.m. on April 12. Confederates bombard Fort Sumter all day. Federal forces return fire starting at 7:30 a.m. but the garrison is too small to man all guns, which are not all in working order in any event. After a 34-hour bombardment, on April 13, Major Anderson surrenders Fort Sumter to the Confederates since his supplies and ammunition are nearly exhausted and the fort is disintegrating under the Confederate cannon fire. Relief ships arrive but can not complete their mission due to the bombardment. Four thousand shells had been fired at the fort but only a few minor injuries were sustained by the garrison. On April 14, Fort Sumter is formally surrendered to the Confederates. One Federal soldier, Private Daniel Hough, is killed, another, Private Edward Galloway, is mortally wounded and four are hurt by an exploding cannon or exploding ammunition or gunpowder from a spark. The cannon was being fired during a salute to the U.S. flag at the surrender ceremony. The garrison is evacuated by the U.S. Navy vessels.
- April 15: President Lincoln calls on the states to provide seventy-five thousand militiamen to recapture Federal property and to suppress the rebellion.