The presidency of Abraham Lincoln began on March 4, 1861, when Abraham Lincoln was inaugurated as the sixteenth president of the United States and ended with his assassination on April 15, 1865, shortly after his second term began. The American Civil War began in the second month of Lincoln's presidency and ended days before his death.

1861

March 1861 March 4 – Abraham Lincoln is inaugurated as the sixteenth president of the United States. In his speech, he says that states cannot secede and that he believes the states are "not enemies, but friends". Hannibal Hamlin becomes vice president of the United States. March 5 – William H. Seward, Salmon P. Chase, Simon Cameron, Edward Bates, Montgomery Blair, Gideon Welles, and Caleb B. Smith become secretary of state, secretary of the treasury, secretary of war, attorney general, postmaster general, secretary of the navy, and secretary of the interior, respectively. Seward and Welles will serve for the entirety of Lincoln's presidency. March 6 – The United States signs a treaty with the Sauk and Fox people. March 11 – The Confederate States of America adopts the Constitution of the Confederate States. March 14 – The Supreme Court issues its decision in Kentucky v. Dennison. It rules that the court cannot force a state to comply with the Extradition Clause of the Constitution. The decision will be overturned in 1987 with Puerto Rico v. Branstad.

April 1861 April 1 – The Morrill Tariff takes effect. April 9 – President Jefferson Davis of the Confederate States orders General P. G. T. Beauregard to fire at United States (Union) forces at Fort Sumter in Charleston Harbor, South Carolina, if they do not surrender the fort. April 12 – The American Civil War begins with the Battle of Fort Sumter when Confederate forces fire upon Fort Sumter. April 13 – The Confederacy wins the Battle of Fort Sumter when Major Robert Anderson surrenders. April 15 – Lincoln calls for 75,000 people to volunteer for the United States Army. He calls for a special session of Congress on July 4. April 17 – Virginia secedes from the United States and joins the Confederacy. April 19 – Lincoln orders that the ports of the Confederacy be blockaded. April 20 – Robert E. Lee leaves the United States Army to join the Confederacy. April 27 – Lincoln expands his blockade of Confederate ports.

May 1861 May 3 – Lincoln orders an expansion of the military. May 6 – Arkansas secedes from the United States and joins the Confederacy. May 10 – The Morrill Tariff is passed, increasing duties to fund the war effort. May 20 – North Carolina secedes from the United States and joins the Confederacy. May 21 – The Confederacy relocates its capital from Montgomery, Alabama, to Richmond, Virginia. May 24 – Arlington House, the home of Confederate General Robert E. Lee, is captured by the Union army.

June 1861 June 8 – Tennessee secedes from the United States and joins the Confederacy. June 20 – Several counties split from western Virginia to form West Virginia and stay in the Union.

July 1861 July 2 – The United States signs a treaty with the Delaware people. July 4 The 37th United States Congress convenes for its first session. Lincoln addresses Congress to call for a larger army. July 11 – The United States signs a treaty of friendship, commerce, and navigation with Denmark. July 17 – The Fiscal Year 1862 appropriations expands the army and the navy. July 21 – The First Battle of Bull Run takes place near Manassas, Virginia. Confederate forces led by General Thomas J. Jackson defeat Union forces led by General Irvin McDowell. Jackson comes to be known as Stonewall Jackson for his actions in this battle. July 25 – The United States offers a bonus of $100 for anyone who serves two years in the Union Army. July 29 – The president is authorized to use the military to suppress rebellion.

August 1861 August 5 – The Revenue Act implements a three-percent income tax. August 6 Lincoln's emergency use of the military is authorized by Congress. The Confiscation Act of 1861 authorizes the government to seize property used by the Confederacy. This is used as legal justification to provide refuge for escaped slaves. The 37th United States Congress adjourns from its first session. August 16 – Lincoln issues a proclamation banning trade with the Confederacy.

September 1861 September 14 – The USS Colorado attacks the steamer Judah at Pensacola, Florida, in the first naval battle of the Civil War.

October 1861 October 24 – The president of Overland Telegraph Company sends Lincoln a telegram from Sacramento, California, the first to be sent across the continent. October 31 – General Winfield Scott retires as Commanding General of the United States Army.

November 1861 November 1 – Lincoln appoints George B. McClellan as Commanding General of the United States Army. November 6 – The United States signs a treaty abolishing stade or brunshausen dues with Kingdom of Hanover. November 15 – The United States signs a treaty with the Potawatomi people.

December 1861 December 2 – The 37th United States Congress convenes for its second session. December 3 – Lincoln delivers the 1861 State of the Union Address. He expresses support for freeing slaves. December 11 – The United States signs an extradition treaty and a postal convention with Mexico.

1862 January 1862 January 15 – Edwin Stanton succeeds Simon Cameron as secretary of war. January 21 – Lincoln nominates Noah Haynes Swayne to the Supreme Court to fill a vacancy left by John McLean. January 24 – The Senate confirms Lincoln's nomination of Noah Haynes Swayne to the Supreme Court. January 27 – Lincoln orders "general movement" against the Confederacy on February 22.

February 1862 February 14 – Lincoln issues an executive order to release people charged with treason if they swear they will not assist the Confederacy. February 20 – Lincoln's eleven-year-old son William Wallace Lincoln dies. He is the second of Lincoln's sons to die. February 25 The Legal Tender Act of 1862 authorizes the distribution of United States Notes as federal currency. The United States signs a treaty of commerce and navigation with the Ottoman Empire.

March 1862 March 6 – Lincoln proposes emancipating slaves with compensation. March 9 – The Battle of Hampton Roads between the Union USS Monitor and the Confederate USS Merrimack ends in a draw. This is the first ever battle between two ironclad warships. March 13 A law is passed forbidding the military from returning escaped slaves. The United States signs a treaty with the Kansa people.

April 1862 April 7 The Battle of Shiloh ends with a victory for Union General Ulysses S. Grant. The United States signs a treaty to suppress the Atlantic slave trade with the United Kingdom. April 16 – Slavery in Washington, D.C. is abolished. Slaveowners are offered $300 in compensation if they swear an oath of allegiance.

May 1862 May 12 – Lincoln issues a proclamation ending blockades of Confederate ports. May 20 – The Homestead Act of 1862 allows settlers to claim up to 160 acres of public land. May 25 – Lincoln issues an executive order seizing railroads and placing them under military control.

June 1862 June 1 – General Robert E. Lee is appointed commander of the Confederate Army of Northern Virginia. June 19 – Slavery is abolished in the federal territories. June 24 – The United States signs a treaty with the Ottawa people of Blanchard's Fork and Roche de Boeuf. June 26 – Lincoln issues an executive order creating the Army of Virginia as a Union counterpart to the Confederate's army of Virginia. June 28 – The United States signs a treaty with the Kickapoo people.

July 1862 July 1 The Union Pacific Railway Company is created under federal law. The same law authorizes the construction of railways and telegraph lines between the Missouri River and the West Coast. Union Major David Hunter includes black soldiers among his forces. July 2 The Morrill Act establishes land grants for universities . A federal oath of office is created. It requires officials to swear that they have never "borne arms against the United States" or assisted those who had. July 4 – Lincoln makes another proposal for compensated emancipation. July 14 – Military pensions are granted to anyone who has served in the military since March 4, 1861, and pension rates are increased. This becomes the most expensive government activity of the era. July 17 The Confiscation Act of 1862 frees slaves of people engaging in rebellion and authorizes the seizure of private property of Confederate leadership. Freedom is granted for any slaves who are serving in a militia, alongside freedom for their mothers, wives, and children. The 37th United States Congress adjourns from its second session. July 19 – The United States signs an agreement with Denmark regarding colonization of the West Indies. July 22 – Lincoln privately informs his cabinet that he intends to emancipate slaves. They encourage him to wait until a major Union victory so it does not seem like an act of desperation for global support.

August 1862 August 17 – The Dakota War of 1862 begins when Dakota people launch an attack against white settlers in Minnesota. August 24 – Lincoln publishes an open letter to Horace Greeley in The New York Times saying he intends to save the Union whether it means freeing no slaves, some slaves, or all slaves. August 31 – The Second Battle of Bull Run ends. Confederate General Stonewall Jackson defeats Union General John Pope.

September 1862 September 17 – Union General George B. McClellan causes Confederate General Robert E. Lee to retreat in the Battle of Antietam. With almost 5,000 men killed, this is the deadliest day in the American Civil War. September 22 – Lincoln issues the Emancipation Proclamation, declaring that all slaves in Confederate states are free effective January 1 if the Confederacy does not surrender.

October 1862 October 21 – The United States signs a treaty of commerce and navigation with Liberia.

November 1862 November – The Republican Party retains both chambers of Congress in the 1862 United States elections.

December 1862 December 1 The 37th United States Congress convenes for its third session. Lincoln delivers the 1862 State of the Union Address. He proposes a colony for freed slaves, advocates a constitutional amendment for compensated emancipation of slavery, and accuses Indian tribes of "a spirit of insubordination" following violent conflict. December 11 – Lincoln announces that he has commuted all death penalties associated with the Dakota War for people who participated in battles instead of massacres. December 13 – Confederate General Robert E. Lee defeats Union General Ambrose Burnside in the Battle of Fredericksburg. December 31 The USS Monitor sinks. West Virginia is authorized to become a state if supported by the people of the region.

1863 January 1863 January 1 The Union government recognizes all slaves in Confederate-claimed territory as free, as declared in the Emancipation Proclamation. This occurs as a wartime measure, and whether it would apply in peacetime remains unclear. Caleb B. Smith's tenure as secretary of the interior ends. January 2 – The Battle of Stones River takes place. January 8 – John Palmer Usher becomes secretary of the interior, filling the vacancy left by Caleb B. Smith.

February 1863 February 17 – The United States signs a second treaty to suppress the Atlantic slave trade with the United Kingdom. February 24 – The Arizona Territory is split from the New Mexico Territory. February 25 – The National Bank Act creates a federal banking system. It includes a national currency and the position of Comptroller of the Currency.

March 1863 March 3 The Idaho Territory is established.