On August 20, 1866, the Irish Republican Brotherhood (IRB), also known as the Fenians, significantly escalated their preparations for an armed rebellion against British rule. The organization actively established arms caches throughout Ireland and increased drilling activities among its local units, despite constant surveillance by the police. The IRB's military council finalized detailed plans for a nationwide uprising, reflecting a growing determination to achieve Irish independence through force. This period marked a critical phase in the Fenian movement's efforts to mobilize for revolution.
