Answer:
April 12th, 1861.
Step-by-step explanation:
I'm assuming you're referring towards the American Civil war, the first conflict of the American Civil war is noted as the Firing of cannons at Fort Sumter. There had been much tension in the US preceding this, but the Election of Abraham Lincoln kickstarted the overarching tensions. Confederates heard of plans to resupply Fort Sumter and decided to attack the strategically adventageous point.