January 29, 1850: Senator Henry Clay of Kentucky introduced the Compromise of 1850, a set of resolutions aimed at diffusing the sectional crisis over the expansion of slavery into newly acquired territories following the Mexican-American War. The compromise was passed in September 1850.

May 30, 1854: The Kansas-Nebraska Act became law. Designed by Senator Stephen Douglas of Illinois, the Act repealed the geographical boundaries set in place by the Missouri Compromise of 1820 by allowing settlers in the new territories of Kansas and Nebraska to decide through “popular sovereignty” whether to permit or prohibit slavery.

May 22, 1856: Just days after delivering his inflammatory “Crime Against Kansas” speech in opposition to slavery in the Kansas Territory, Senator Charles Sumner of Massachusetts was attacked in the Senate Chamber by Representative Preston Brooks of South Carolina, who severely beat the senator with a cane.

November 6, 1860:  Abraham Lincoln was elected president of the United States.

November 10, 1860: James Chesnut of South Carolina became the first Southern senator to withdraw from the Senate.

November 11, 1860: James Hammond of South Carolina withdrew from the Senate.

December 18, 1860: Kentucky senator John J. Crittenden introduced a compromise resolution aimed at averting war. The “Crittenden Compromise,” which was rejected, proposed several constitutional amendments, including one that would extend to the Pacific Ocean the line established by the 1820 Missouri Compromise.

January 12, 1861: Albert Brown of Mississippi withdrew from the Senate.

January 21, 1861: Jefferson Davis of Mississippi withdrew from the Senate. “The states are sovereign,” he declared, bidding a final farewell to his colleagues. Four other Southerners withdrew from the Senate on this day, followed by ten others in the months ahead.

January 29, 1861: Kansas became the 34th state.

March 2, 1861: The Senate passed the Morrill tariff bill, significantly increasing tariff rates in order to encourage industrial growth. Passage of this legislation had been held up by Southern senators, now absent, who supported low tariffs.

March 4, 1861: Abraham Lincoln took the oath of office in the shadow of the Capitol’s unfinished cast-iron dome. “We must not be enemies,” he pleaded to the people of the seven Southern states that had seceded and formed the Confederacy, “though passion may have strained it must not break our bonds of affection.”

April 12, 1861: Confederate forces attacked Fort Sumter, near Charleston, South Carolina. Following the Union surrender of the fort, President Lincoln issued a proclamation calling forth the state militias, to the sum of 75,000 troops, and summoned Congress to return for an extraordinary session on July 4, 1861.

April 19, 1861: The Sixth Regiment of Massachusetts arrived in Washington bloodied and exhausted after encountering angry mobs of Southern sympathizers in Baltimore. Joining troops already quartered in the Capitol, they made their camp in the Senate Chamber.

April 21, 1861: Construction began on several large brick ovens in the basement of the center section of the Capitol. Used to feed the growing number of troops in the city, the Capitol bakery remained in operation until October 1862.

April 25, 1861: Senator Stephen Douglas speaks before the Illinois Legislature.

July 4, 1861: The 37th Congress convened for an extraordinary session in accordance with President Lincoln’s April 15 proclamation. The Senate had met in special session until March 28, and now returned again to meet the war-time emergency.

July 11, 1861: By a vote of 32 to 10, the Senate expelled 10 absent Southern members.

July 21, 1861: Members of Congress gathered about 30 miles outside of Washington, some with picnic lunches, to witness the Battle of Bull Run. In what became known as the “Picnic Battle,” civilian spectators expecting an easy Union victory were swept up by Union troops fleeing the battlefield in retreat.

August 6, 1861: The first Confiscation Act became law, allowing Union forces to seize all property–including enslaved persons–used to aid the Confederate cause.

October 21, 1861: Senator Edward D. Baker of Oregon died at the Battle of Ball’s Bluff, the only United States senator ever to die in a military engagement.

November 8, 1861: Former senators James M. Mason of Virginia and John Slidell of Louisiana were captured en route to England on the British mail steamer Trent , halting their diplomatic mission for the Confederacy.

December 4, 1861: The Senate expelled John C. Breckinridge of Kentucky. Breckinridge had become a general in the Confederate army, despite the fact that Kentucky remained in the Union.

December 10, 1861: The Joint Committee on the Conduct of the War began overseeing the war effort. Chaired by Senator Benjamin Wade of Ohio, this congressional investigating committee met 272 times over the next four years.

February 5, 1862: The Senate expelled Indiana senator Jesse Bright for disloyalty, the last senator expelled for support of the Confederacy.

February 18, 1862: The Confederate Congress convened in Richmond, Virginia. Among the members of the newly formed Confederate Senate were several former U.S. senators.

February 22, 1862: A joint session of Congress gathered in the House Chamber to commemorate the 130th anniversary of George Washington’s birth by reading Washington’s 1796 Farewell Address. The reading of this address later became an annual Senate tradition.

April 16, 1862: The District of Columbia Compensated Emancipation Act became law. Originally sponsored by Senator Henry Wilson of Massachusetts, the act freed slaves in the District of Columbia and compensated owners up to $300 for each freeperson.

May 15, 1862: The Senate passed the Homestead Act. Signed into law by President Lincoln on May 20, the act was intended to bolster western migration by offering settlers the chance to earn ownership by settling and farming federal land.

June 6, 1862: The Senate approved the Revenue Act of 1862, which became law on July 1. Senator William Pitt Fessenden of Maine was a principle architect of law which provided the U.S. government with revenue to fund the war effort.

June 28, 1862: The Senate passed the second Confiscation Act, declaring free the slaves of anyone found guilty of engaging in the rebellion. The president signed the act into law on July 17, 1862.

July 1, 1862: The Pacific Railway Act became law after Congress agreed on a northern route to the Pacific, providing for the construction of the nation’s first transcontinental rail line.

July 2, 1862: President Lincoln signed the Morrill Land Grant Act, which set aside federal lands to create colleges to “benefit the agricultural and mechanical arts.”

September 20, 1862: Following the Second Battle of Bull Run, the Capitol was briefly used as a hospital for thousands of wounded troops.

November 1862: Congressional elections were held across the United States.

January 1, 1863:  Nearly nine months after Congress passed the District of Columbia Compensated Emancipation Act, President Lincoln issued the Emancipation Proclamation, declaring free “all persons held as slaves within any States, or designated part of the State, the people whereof shall be in rebellion against the United States.”

February 25, 1863: Congress established a national banking system, creating a system of national banks and promoting the development of a uniform national currency.

March 3, 1863: The Conscription Act became law. Sponsored by the chairman of the Senate Committee on Military Affairs, Senator Henry Wilson of Massachusetts, the act established the first national draft system.

June 20, 1863: West Virginia was admitted as a state. When Virginia seceded in 1861, a majority of the delegates representing the northwestern counties of the state voted against secession. Meeting in Wheeling the following month, delegates from these counties voted to remain loyal to the Union and form a new state.

December 2, 1863: Thomas Crawford’s Statue of Freedom was installed atop the newly completed cast-iron Capitol dome, a symbolic event signifying the enduring nation in a time of civil war.

December 7, 1863: The 38th Congress convened in Washington.

January 25, 1864: The Senate adopted a rule requiring members to swear the so-called “Ironclad Test Oath,” a pledge of future loyalty as well as an affirmation of past fidelity to the country. Senator James A. Bayard of Delaware resigned in protest four days later.

April 6, 1864: The Senate passed the Thirteenth Amendment by a vote of 38 to 6.

July 4, 1864: The Wade-Davis bill, Congress’s plan for reconstruction of the South, was pocket vetoed by President Lincoln.

October 31, 1864: Nevada became the 36th state.

November 1864:  Presidential and congressional elections were held across the United States.

January 31, 1865:  The House of Representatives passed the Thirteenth Amendment by a vote of 119 to 56.

March 3, 1865:  Congress established the Freedmen’s Bureau to provide food, shelter, clothing, and land to displaced Southerners, including newly freed African Americans.

March 4, 1865: President Lincoln’s second inauguration took place on the eastern portico of the Capitol. Beneath the newly completed dome, the President urged his countrymen to move forward, “with malice toward none. . . to bind up the nation’s wounds.”

April 9, 1865:  Confederate general Robert E. Lee surrendered at Appomattox Court House in Virginia.

April 14, 1865: President Lincoln was shot while attending a play at Ford’s Theater in Washington, D.C. He died the morning of April 15.

April 15, 1865: Vice President Andrew Johnson was sworn in as president of the United States. As a Tennessee senator, Johnson had been the only Southern senator to remain loyal to the Union after his state seceded.

April 19-21, 1865: In the Capitol Rotunda the body of President Lincoln lay in state on a hastily constructed catafalque beneath the newly completed dome.

May 22, 1865: The Joint Committee on the Conduct of the War issued its final report after four years of investigating various war-related issues, including corruption in military supply contracts, the mistreatment of Union prisoners by Confederate forces, the massacre of the Cheyenne Indians, and gunboat construction.

May 23-24, 1865: Washington’s celebrations marking the end of the war culminated with the grand review of the Union armies. “As far as the eye could see up Pennsylvania Avenue seemed like a river of life,” Senate doorkeeper Isaac Bassett recalled of the scene.

December 6, 1865: The Thirteenth Amendment was ratified by the states, abolishing slavery “within the United States, or any place subject to their jurisdiction.”