Coming at the approximate halfway point between the battle of Fort Sumter and the surrender of the Confederacy, the Battle of Gettysburg in July 1863 splits the American Civil War neatly in two. It marked a significant turning point in the bloodiest war in American history, with the hitherto unstable balance of power settling on the side of the Union.

Abraham Lincoln’s legendary address at the Gettysburg burial site, made 150 years ago this month on 19th November 1863, was less than two minutes long and yet has been heralded as one of the greatest speeches in history. In just 272 words, Lincoln managed to reaffirm the crux of what the Civil War was all about. It was a chance for the Union to ensure that their “government of the people, by the people, for the people, shall not perish from the earth”, and prove the superiority of federal control, as opposed to sovereign states.

By quoting the Declaration of Independence’s immortal line that “all men are created equal”, Lincoln’s speech also reaffirmed the war’s connection to the “peculiar institution” that was slavery. The creation of the Cotton Gin in the late 18th century, which made cotton cheap and simple to produce, saw a huge increase in the number of slaves, particularly in the Deep South. The entrenchment of slavery into the South created an economy and society dependent on the institution, whilst rapid industrialisation and a flourishing free-labour society in the North resulted in two significantly contrasting and conflicting cultures. By 1858 as Lincoln accepted the Republican Party’s nomination as Illinois’s senator, the ever-increasing rift between the two cultures was an unavoidable topic. His prophetic speech claiming that “a house divided against itself cannot stand” highlighted his expectation that a civil war would be unavoidable.

Although numerous attempts at compromise over the first half of the 19th century had been made, none proved successful or permanent. The 1820 Missouri Compromise, which prevented slavery in the West north of the 36° 30´ latitude line with the exception of Missouri, was undone by the 1854 Kansas-Nebraska Act, which declared that popular sovereignty would dictate whether these newly created states (North of this line) would allow slavery. The subsequent rush to Kansas by both pro- and anti-slavery groups to sway the vote led to a series of confrontations known as ‘Bleeding Kansas’, which hinted at the violence to come.

After Lincoln and the newly-formed Republican Party’s success in the 1860 Presidential election, seven states in the Deep South seceded from the Union to form the Confederate States of America, an action which the Union quickly declared illegal. A month after Lincoln came to office in March 1861, the Confederacy attacked the Union controlled garrison in South Carolina named Fort Sumter, and the President prepared to retaliate against the now 11 state-strong Confederacy. After decades of hostilities, the Civil War had officially begun.

Despite the Union’s substantial advantage in numbers (22 million men opposed to the South’s 9 million) and their more dependable economy, including a supply of steel for weapons, the next two years leading up to Gettysburg were surprisingly balanced. A series of indecisive battles enabled the South to maintain its defence of a society that refused to be controlled and conquered by Northern authority. However, the Union’s victory at Gettysburg combined with the Confederate surrender of Vicksburg, their most important stronghold along the Mississippi River, arguably marks the point at which the Union’s eventual victory became clear.

When Lincoln addressed the crowd at the site where 51,000 causalities had occurred during the Battle of Gettysburg (more than at any other battle in American history) he had an important job to do in boosting morale. Having issued the Emancipation Proclamation in January 1863 and officially ending the issue of slavery in the Southern states, he now had to remind his country what its men had been fighting and dying for: liberty and equality.

For Lincoln, the war was the unfortunate price that had to be paid to keep the North and South united as a nation. Whilst the divisive issue of slavery had to be addressed as part of this, both sides understood the war to be a fight to determine how the nation would be run. Reflecting this, Lincoln’s Gettysburg Address put the protracted Civil War back into context; it was a matter of life or death, not just for the individual soldiers, but for the nation as a whole.