Lincoln's private life in these years was unsettled. He fell hard for a young woman named Ann Rutledge, who had also come from Kentucky to New Salem. She died of typhoid fever in August 1835. Lincoln sank into a serious depression and, by some accounts, contemplated suicide. He courted another woman briefly and wrote her a letter effectively releasing her from any obligation; she declined to marry him. In 1839, he met Mary Todd in Springfield. She was the daughter of a wealthy Kentucky lawyer and businessman, educated and sharp-tongued. They became engaged, Lincoln broke it off in early 1841, and then they reconciled and married on November 4, 1842.

The marriage was turbulent. Mary was at times verbally and physically abusive toward her husband, and Lincoln suffered throughout his life from what he called melancholy, a condition now recognised as clinical depression. They had four sons, only one of whom, Robert, lived to adulthood. Their second son Eddie died in 1850, probably of tuberculosis. Their third son Willie died of fever in the White House in February 1862. Their youngest, Tad, survived the presidency but died at eighteen. The deaths of the children were profound blows to both parents. Lincoln carried grief the way other men carry a coat.

As a lawyer, Lincoln was formidable. He appeared before the Illinois Supreme Court in more than four hundred cases and handled virtually every kind of dispute a frontier lawyer might encounter. One of his most celebrated cases came in 1858, when he defended a man accused of murder. A witness claimed to have seen the crime clearly by moonlight. Lincoln produced a farmer's almanac in court showing that the moon that night was at too low an angle to provide the visibility the witness claimed. His client was acquitted. Lincoln was also the only president ever to hold a patent, for a flotation device designed to help riverboats navigate shallow water. It was never commercialised, but it showed the restless, practical turn of his mind.

The event that dragged Lincoln back into politics with full force was the Kansas-Nebraska Act of 1854. Illinois Senator Stephen Douglas, a Democrat, proposed that the question of whether slavery would be permitted in new western territories should be decided by the settlers themselves, a principle called popular sovereignty. The act passed narrowly, but it effectively reopened the possibility of slavery spreading into regions where it had been barred. Lincoln was outraged. He delivered what became known as his Peoria Speech in October 1854, declaring his opposition to slavery's extension, and he would give an estimated hundred and seventy-five speeches on the subject over the next six years.

The Kansas-Nebraska Act split the Whig Party beyond repair. A new party, the Republicans, formed from its anti-slavery wing, combined with members of smaller anti-slavery movements. Lincoln initially held back, hoping the Whigs could be revived, but by 1856 he had joined the Republicans and was helping to build the Illinois branch of the party. He told allies that year: 'I now do no more than oppose the extension of slavery.' It was a careful line, but it was also a real one. He was not yet an abolitionist. He was a man who believed slavery was morally wrong and constitutionally protected where it already existed, and who was determined that it should not spread one acre further.

The Supreme Court's ruling in the Dred Scott case in 1857 sharpened the argument further. The court's chief justice, Roger Taney, ruled that enslaved people could never be citizens, and that Congress had no power to ban slavery from the territories. The decision struck Lincoln as not merely wrong but dangerous: an attempt to put slavery permanently beyond the reach of democratic politics. He argued that it contradicted the Declaration of Independence, which stated that all men are created equal. That document, Lincoln insisted, was the 'sheet anchor' of American republicanism. It was a phrase he would return to for the rest of his life.

In 1858, Lincoln challenged Douglas directly for his Senate seat. The Republican-controlled Illinois legislature would choose the winner, and Lincoln and Douglas staged seven public debates across the state, drawing thousands of spectators each time. The atmosphere was closer to a sporting contest than a political forum. Lincoln delivered what became known as his House Divided Speech upon receiving the nomination: 'A house divided against itself cannot stand. I believe this government cannot endure, permanently half slave and half free.' Douglas won the legislative vote, but Lincoln had made himself a national figure. Newspapers across the North were already mentioning him as a possible presidential candidate.

In February 1860, Lincoln travelled to New York and delivered a speech at Cooper Union in Manhattan, arguing that the Founding Fathers had restricted slavery in the territories through the Northwest Ordinance and that morality demanded opposition to its spread. The audience found him awkward, even ungainly. But the journalist Noah Brooks reported that no man had ever made such an impression on a New York audience on first appearance. The speech put Lincoln squarely in contention for the Republican presidential nomination. When asked about his ambitions, Lincoln said, with characteristic dryness: 'The taste is in my mouth a little.'

At the Republican National Convention in Chicago in May 1860, Lincoln won the nomination on the third ballot, with a former Democrat from Maine, Hannibal Hamlin, chosen as his running mate to balance the ticket. The Democratic Party split: the Northern wing nominated Douglas, while Southern delegates backed the sitting vice president, John Breckinridge. A fourth candidate, John Bell, ran on a platform of preserving the Union without addressing slavery directly. Lincoln made no public campaign appearances, relying on the party's machinery and on a nationwide Republican youth movement, the Wide Awakes, to generate enthusiasm.

On November 6, 1860, Lincoln was elected as the first Republican president, winning just under forty per cent of the popular vote in a four-way race. He carried every free state, along with California and Oregon, and won the electoral college decisively. Not a single ballot was cast for him in ten of the fifteen slave states. The result was unambiguous in the North. In the South, it was read as a declaration of war.

Before Lincoln could even take the oath of office, the country began to fracture. South Carolina voted to secede from the United States in December 1860. By February 1, 1861, six more states had followed. They formed the Confederate States of America, elected Jefferson Davis as their provisional president, and began seizing federal property across the South. The upper South and the border states hesitated, watching to see what would happen next. Lincoln, still in Springfield, gave an emotional farewell address on February 11, 1861, and travelled to Washington in partial disguise, wearing a soft felt hat and hunching to conceal his height, after intelligence suggested a plot to kill him in Baltimore.

In his first inaugural address, delivered on March 4, 1861, Lincoln tried one last time to reassure the South. He had no intention, he said, of interfering with slavery where it existed. He appealed directly to the Southern people: 'We are not enemies, but friends... The mystic chords of memory, stretching from every battle-field, and patriot grave, to every living heart and hearthstone... will yet swell the chorus of the Union, when again touched... by the better angels of our nature.' The appeal went unanswered. A month later, on April 12, 1861, Confederate forces opened fire on the federal garrison at Fort Sumter in Charleston harbour. The Civil War had begun.

Lincoln's response was immediate and sweeping. He called for seventy-five thousand militiamen to suppress the rebellion, a call that forced every remaining state to choose a side. Virginia, North Carolina, Tennessee, and Arkansas joined the Confederacy. Lincoln imposed a naval blockade on Confederate ports, suspended the legal right of habeas corpus, allowing arrests without formal charges, and authorised the spending of funds before Congress had appropriated them. The chief justice of the Supreme Court, Roger Taney, ruled that only Congress could suspend habeas corpus. Lincoln simply ignored the ruling and continued the policy. Roughly fifteen thousand civilians were detained without trial during the war.

In selecting his cabinet, Lincoln made a decision that became famous: he appointed his chief political rivals to the most powerful posts. His main opponent for the Republican nomination, William Seward, became Secretary of State. He explained his reasoning plainly: 'We need the strongest men of the party in the Cabinet.' The historian Doris Kearns Goodwin later described the group as a team of rivals. It was a characteristically Lincolnian move: ego subordinated to purpose, ambition redirected toward the larger task.

Lincoln had no military experience beyond his brief and uneventful militia service in 1832, but he taught himself strategy with the same relentless self-education that had made him a lawyer. He read military manuals, met twice a week with his cabinet, and supervised the selection and dismissal of generals with a patience that wore visibly thin. His first general-in-chief, George McClellan, built formidable defences around Washington but moved with agonising slowness against the Confederates. McClellan privately despised Lincoln, calling him a gorilla in letters to his wife. Lincoln bore it without complaint and kept pressing for action. When McClellan's Virginia campaign stalled in 1862, Lincoln removed him, then restored him after Confederate forces under Robert E. Lee crossed into Maryland and the two armies fought at Antietam in September 1862, the bloodiest single day of the war.

McClellan then refused to pursue Lee's retreating army, and Lincoln removed him for good. The generals who followed, Burnside and then Hooker, both suffered serious defeats. It was not until Ulysses Grant captured the Confederate fortress at Vicksburg in July 1863 and took control of the Mississippi River, splitting the Confederacy in two, that Lincoln found his general. 'I can't spare this man,' Lincoln had said after critics attacked Grant following the Battle of Shiloh in 1862. 'He fights.' Lincoln promoted Grant to command of all Union armies in 1864, and Grant's Overland Campaign, though brutally costly, drove Lee's forces back toward Richmond.

Internationally, Lincoln worked hard to keep Britain and France from recognising the Confederacy or intervening on its behalf. The most dangerous moment came in late 1861, when the United States Navy stopped a British mail ship called the Trent on the high seas and seized two Confederate envoys. Britain protested furiously and the two countries edged toward war. Lincoln resolved the crisis by releasing the envoys. He told his Secretary of State Seward: 'One war at a time.' It was the right call. Britain never recognised the Confederacy, and the diplomatic isolation of the Southern cause would prove decisive.

The war also forced Lincoln to confront the question of slavery in ways he had not anticipated. Two Union generals issued emancipation orders in 1861 and 1862 on their own authority; Lincoln overrode both, judging that the border states, which still held enslaved people and had not seceded, might be pushed out of the Union if he moved too fast. He was playing a longer game. In August 1862, when the newspaper editor Horace Greeley publicly demanded that Lincoln embrace emancipation, Lincoln replied with a letter that has become one of the most quoted statements of his presidency: 'My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery.' It was a politically careful answer. But by the time he wrote it, the Emancipation Proclamation was already drafted.

On September 22, 1862, buttressed by the Union victory at Antietam, Lincoln issued a preliminary proclamation: unless the Confederate states returned to the Union by January 1, 1863, all enslaved people in the states still in rebellion would be declared free. The Confederate states did not return. On the first of January 1863, Lincoln signed the final Emancipation Proclamation. He had been shaking hands at a New Year's reception for three hours and his right hand trembled. He paused, then steadied himself. 'I never, in my life, felt more certain that I was doing right than I do in signing this paper,' he said.

The Proclamation did not free every enslaved person in America. It applied only to the states in active rebellion, not to the border states still in the Union. It was a war measure, grounded in Lincoln's authority as commander-in-chief, not a constitutional amendment. But its moral and practical consequences were enormous. Across the United States, on the night of December 31, 1862, Black people, enslaved and free, gathered in churches and meeting halls to hold what they called Watch Night services, waiting for Freedom's Eve to become Freedom's Morning. For the Union armies, emancipation became a military objective. As they advanced south, thousands escaped bondage. Enlisting freed Black men as soldiers became official policy. By the war's end, roughly a hundred and eighty thousand Black soldiers had served in the Union army.

Lincoln understood that the Proclamation, as a war measure, could be challenged or reversed once the fighting stopped. He pressed Congress for a constitutional amendment that would abolish slavery permanently and everywhere. The Senate passed it in April 1864. The House fell short on the first vote. Lincoln made the amendment's passage a central promise of his re-election campaign and, after winning that campaign, pushed hard for the second House vote. It passed on January 31, 1865. After ratification by enough states in December 1865, it became the Thirteenth Amendment to the United States Constitution, abolishing slavery and involuntary servitude throughout the country. Lincoln did not live to see ratification, but he had made it happen.

On November 19, 1863, Lincoln travelled to Gettysburg, Pennsylvania, to dedicate the cemetery on the battlefield where, four months earlier, the two largest armies of the war had fought for three days and left more than fifty thousand men dead or wounded. The main address that day was given by a celebrated orator named Edward Everett, who spoke for two hours. Lincoln followed with a speech of roughly two hundred and seventy words. He told the crowd that the nation had been 'conceived in liberty and dedicated to the proposition that all men are created equal', and that the dead had died so that 'government of the people, by the people, for the people, shall not perish from the earth.' Everett wrote to Lincoln afterward: 'I should be glad if I could flatter myself that I came as near to the central idea of the occasion, in two hours, as you did in two minutes.'

By the summer of 1864, Lincoln feared he would lose the presidency. Grant's campaign in Virginia was grinding and costly. The Confederate army under Jubal Early raided to within sight of Washington itself. Anti-war Democrats nominated McClellan, and many Republicans privately believed Lincoln could not win. Lincoln drafted a confidential memorandum pledging that if he lost, he would cooperate with his successor to save the Union before the inauguration, because his successor would have been elected on terms that made saving it impossible afterward. He sealed it and asked his cabinet to sign it without reading it.

Then the military situation shifted. The fall of Atlanta in September 1864, followed by sweeping Union victories in the Shenandoah Valley in October, transformed the mood of the North. Lincoln was re-elected with just over fifty-five per cent of the popular vote, carrying all but three states. At his second inauguration on March 4, 1865, he delivered an address that made no attempt at triumph. He spoke of the war's cause without gloating and ended with a passage that has been carved into the Lincoln Memorial in Washington: 'With malice toward none; with charity for all; with firmness in the right, as God gives us to see the right, let us strive on to finish the work we are in; to bind up the nation's wounds.'

A month later, on April 9, 1865, Lee surrendered to Grant at Appomattox Court House in Virginia. The war was effectively over. Lincoln had already begun thinking hard about Reconstruction, the process of bringing the Southern states back into the Union and establishing the place of four million freed people in American life. His approach was deliberately generous. When a general asked how defeated Confederates should be treated, Lincoln said: 'Let 'em up easy.' He signed a bill establishing the Freedmen's Bureau, a federal agency designed to help formerly enslaved people with land, labour contracts, and basic needs. He proposed that Southern states be readmitted when ten per cent of their voters swore loyalty and agreed to abolish slavery.

The Radical Republicans in Congress found Lincoln's terms too lenient and pushed for harsher conditions. Lincoln pocket-vetoed their alternative plan. It was a genuine disagreement about how far Reconstruction should go, and Lincoln was still navigating it when he made his last public address, on April 11, 1865, speaking from a White House window to a crowd gathered on the lawn below. He said he favoured extending the vote to Black men who were educated or who had served as soldiers. John Wilkes Booth stood in that crowd and listened. According to those nearby, Booth said: 'That is the last speech he will ever make.'

Booth fired three nights later. Lincoln died on the morning of April 15, 1865, in the small back bedroom of Petersen House, surrounded by cabinet members, military officers, and his wife. Secretary of War Edwin Stanton, who had worked more closely with Lincoln than any other senior official, is reported to have said as Lincoln breathed his last: 'Now he belongs to the ages.' Two weeks later, Booth was tracked to a farm in Virginia and shot dead by a Union sergeant named Boston Corbett.

Lincoln's body lay in state first at the White House, then in the Capitol rotunda, and then travelled for two weeks on a funeral train from Washington to Springfield, Illinois, stopping at cities across the North where hundreds of thousands came to pay their respects. Many more stood silently along the tracks as the train passed. Walt Whitman, the American poet who had spent the war years nursing wounded soldiers in Washington hospitals, wrote four elegies for Lincoln, including 'O Captain! My Captain!' and 'When Lilacs Last in the Dooryard Bloom'd'. Lincoln was buried at Oak Ridge Cemetery in Springfield, where his tomb still stands.

What Lincoln left behind was not simply a preserved Union or even the abolition of slavery, though both were real and immeasurable. He left a redefinition of what America was for. He had taken the Declaration of Independence, a document most politicians of his era treated as rhetorical decoration, and made it the moral foundation of the republic: the claim that all men are created equal was not an aspiration to be managed but a commitment to be honoured, even at the cost of a war that killed more than six hundred thousand people. The formerly enslaved orator Frederick Douglass said of Lincoln that in his company he was never reminded of his humble origin or his unpopular colour. That was not nothing. That was, for its time, nearly everything.

The Lincoln Memorial, dedicated in Washington in 1922, became one of the most visited public spaces in the country, a place where every subsequent generation of Americans has come to argue about what Lincoln meant and whether the country has yet fulfilled what he promised. His face appears on the penny and on the five-dollar bill. His words are carved in stone. His story is told in hundreds of biographies, dozens of films, and in the arguments Americans still have about race, democracy, and what a government of the people is actually obligated to do. He came from a one-room log cabin in Kentucky, taught himself to read by firelight, and died in a boarding-house bedroom across the street from a theatre. What happened between those two rooms changed the world.