Which event significantly influenced British public opinion against the Confederacy during the Civil War?

The Trent Affair was a pivotal incident that swayed British public opinion against the Confederacy during the Civil War. It involved the seizure of two Confederate diplomats, James Mason and John Slidell, by Union forces from the British mail ship, the RMS Trent. This action was seen as a violation of international law and an affront to British sovereignty, causing an uproar in Britain and increasing sympathy for the Confederacy among the British populace.

While the British government ultimately did not intervene militarily, the affair sparked intense debate and highlighted the delicate relationship between the United States and Britain at the time. The outrage in Britain was not solely about the diplomatic misstep; it also illuminated the broader issues surrounding the war, including notions of honor and legal rights, which had significant implications for British attitudes toward the conflict. This incident helped cement a sense of division regarding support for the Union versus the Confederacy among the British public.

The other events listed had their own significance during the Civil War, but none had the direct and immediate impact on British public sentiment as the Trent Affair did. The Battle of Bull Run, for instance, established the conflict's severity but did not influence international opinion as profoundly. The Emancipation Proclamation, while changing the focus of the war