states. A convention (in Richmond) debating Virginia's fate was in progress (it began in February), and the delegates had voted NOT to secede. BUT - South Carolina fired on Fort Sumter (on April 12), and Lincoln called for each state to provide troops to fight those who had seceded (Virginia's quota was 3,500), and that turned the tide.

Earlier in April, Virginian John Baldwin met with Lincoln in the White House in an attempt to reach a compromise, or some type of agreement, to avoid the looming conflict. Lincoln never mentioned slavery as an issue - his biggest concern was losing the Federal tariffs if Southern states left the Union.

You could argue that South Carolina seceded because of slavery, so slavery drug Virginia in. But slavery was not the reason the delegates at the convention changed their votes. And Lincoln had voiced support for the Corwin Amendment, which would have preserved slavery. Virginia was hoping for a compromise to avoid war, Robert E. Lee did not think Virginia was going to secede. (If slavery was a cause, so was the Union's refusal to leave Fort Sumter, as was SC's firing on Sumter, as was Lincoln's call for troops (including Virginia troops) to march across Virginia soil to fight the deep Southern states.) And the South was being battered by the tariffs.

To borrow a quote - "it's complicated".