On the sidelines of the commemorations marking the 50th anniversary last month of the pivotal civil rights march from Selma to Montgomery, which was led in 1965 by Dr. Martin Luther King, a group known as Students Unite planned a peaceful march to the Live Oak cemetery, a burial place for Confederate soldiers that includes the grave of Edmund Winston Pettus.

Pettus was a Confederate general and a member of the Ku Klux Klan, and the bridge that was a crucial crossing point for the 1965 marchers, who were effectively demanding an end to apartheid, was named after him. Students Unite was continuing a campaign waged over the decades to rename the bridge.

The group’s plan for a demonstration was thwarted, however, by the prospect of a confrontation with a small but vocal band of people who identify with the Confederacy that was defeated a century and a half ago in the American Civil War. It served as a reminder that in the minds of some, the civil war, fought chiefly, albeit not exclusively, over the divisive institution of slavery, never quite ended.

It did, of course — not long after the Confederate general Robert E. Lee surrendered to Unionist commander Ulysses S. Grant on April 9, 1865. Five days later — and 150 years ago today — the president whose leadership was pivotal to the Unionist cause, lay dead. Abraham Lincoln had been shot the previous day, during a night out at the theatre, by a prominent actor whose stage talents he admired. John Wilkes Booth had conspired in the preceding months to kidnap the president with the intention of delivering him to the Confederate high command, which in his view could then have demanded the Union’s acquiescence to a bifurcation of the US. He failed to pull that off, and his next best bet was a decapitation: The plan was to kill Lincoln, vice-president Andrew Johnson and Secretary of State William Seward, thereby provoking a crisis that would enable the Confederacy politically to make up for its losses on the battlefield.

Only one part of the plot succeeded, however. The 16th president of the US became the first one to be assassinated. Seward survived an attack, and the man deputed to kill Johnson got cold feet. The latter succeeded Lincoln but proved to be an exceptionally unpopular president and faced impeachment three years later. The US, nonetheless, survived intact.

What’s more, the Republican party, which had been formed in 1854, just six years before it put up Lincoln as a presidential candidate, more or less monopolized the White House until Franklin D. Roosevelt’s ascendancy during the Great Depression in 1932. There is, of course, considerable irony in the fact that today’s Republicans are key defenders of “states’ rights”, a slogan that was once a byword for the right to perpetuate slavery.

In his initial incarnation as a nationwide politician, Lincoln had not questioned that right, declaring in his first inaugural address that he did not believe he had the right to overturn slavery in states where it existed. He insisted, however, that the slave terrain could not be extended. And he appears to have realized some years before he became president that “this nation cannot exist half slave and half free.” His ascendancy nonetheless triggered a string of secessions, leading to a short-lived entity know as the Confederate States of America. Lincoln was no militarist, but felt obliged to preserve the sanctity of the US. In his second inaugural address — delivered on March 4, 1865, less than six weeks before he was assassinated — he summed up the dilemma: “Both parties deprecated war, but one of them would make war rather than let the nation survive, and the other would accept war rather than let it perish, and the war came.”

It cost lives on a scale thereto unprecedented — and thereafter unequalled — in the US, and for much of his tenure at the helm Lincoln’s countenance tended to be appropriately mournful. The Union’s triumph wasn’t by any means a foregone conclusion: there were a number of occasions on which cannon smoke was visible from the White House windows and whiffs of cordite wafted through its portals. All too often a succession of incompetent or reticent generals wrested defeat from the jaws of victory.

But eventually the tide turned, arguably in part because in the middle of the war Lincoln issued the Emancipation Proclamation, liberating all slaves, which became the 13th Amendment in 1865. A hundred years later, however, the descendants of slaves were still striving for civil and voting rights. It was a different President Johnson — Lyndon, not Andrew, but a successor nonetheless to the legacy of an assassinated head of state — who pushed for and signed the civil rights and voting rights acts of 1964 and 1965. The ignominy Lyndon Johnson attracts on account of his role in the Vietnam War is entirely justified, notwithstanding his legislative contributions to the formal end of post-slavery American apartheid. And it is notable that 50 years on key issues remain unresolved, amid evidence of regression on some fronts, including voting rights and institutional segregation.

It’s worth remembering, though, that in 1865 Lincoln was greeted on his re-election by a missive from a recently formed International Workingmen’s Association, based in London and headed by a German exile called Karl Marx, which described the re-elected president as “the single-minded son of the working class” who would “lead his country through the matchless struggle for the rescue of an enchained race and the reconstruction of a social world”.

Just a few months later, Marx and the IWA felt obliged to dispatch a second message, addressed this time to Andrew Johnson, hailing Lincoln as “a man neither to be browbeaten by adversity nor intoxicated by success,” and as “one of the rare men who succeed in becoming great without ceasing to be good.”

That’s an epitaph to which no one could seriously object, barring the unreconstructed upholders of the confederacy, who may wish to place Booth on the kind of pedestal chosen for Nathuram Godse by the forces of Hindutva in India.