On August 1, 1864, the British Empire, by far the world's greatest military power, had taken a stance of neutrality in the American Civil War.
The empire was led by Lord Palmerston, a statesman known for his caution in placing British interests ahead of his ideals. Despite Palmerston's feelings that Union forces were the aggressors, that the Americans fomented terrorism in Ireland, and that the American President Lincoln was a tyrant, the most Palmerston had been willing to concede to the Confederate States of America was recognition as a belligerent which might one day become a nation. Despite urging to enter the American war from the French emperor, Napoleon III, who hungered for glory and sought to distract his people from domestic scandal and, like Palmerston, sympathized with the Confederates, the most Palmerston had done was to send British troops to Canada when faced by an act of American piracy.
On August 1, 1864, Lincoln's forces, led by General William Tecumseh Sherman, whose name was shortly to become a byword for cruelty in war, all but surrounded the city of Atlanta. In one month Sherman would burn the city to the ground. Now, suppose Palmerston had reliable intelligence on Sherman's plans for Atlanta? In Palmerston's eyes, the Confederates had the just cause, and were fighting for freedom against an enemy of the British empire. With orders carried aboard a swift ship, the British could have intervened in the American war, attacking from Canada, preventing an atrocity and dealing a mortal blow to an enemy nation with which Britain had fought two wars.
In the end, Palmerston did nothing. The city of Atlanta was burned to ashes and the Confederates were ground under the heels of tyrants.
Should Palmerston have acted? And if he had, what would the consequences have been for the British empire and the world?