[GOPcapitalist]

Lincoln's executive order was issued two days after Virginia seceded

Virginia's secession did not occur until the referendum, which if I recall correctly, was after the blockade. I'll have to pull the documents, but if my memory serves me, there was an order and an extension following that order that included some non-seceded states.

[x]

The initial blockade proclamation issued after the Virginia convention's initial secession vote did not include that state. But after the state government seized federal facilities within the state, including the Navy Yard near Norfolk, the proclaimed blockade was extended to Virginia and North Carolina. The Confederate flag was already flying over Richmond, and apparently the state had already proposed that city to the Confederacy as its new capitol.

From the unionist point of view, unilateral secession was impossible. Therefore, a powerful faction in the state was already in rebellion against the legitimate government and the blockade was justified. The federal contention was that the referendum took place under conditions of "virtual martial law." I don't have the information to assess that claim, but it's something that should be investigated. In any event, the unionist perspective was that the rebellion was already underway in Virginia.

It's also worth noting that while a blockade may be an act of war, a declared or intended blockade is not an actual blockade, and hence no act of war. Lincoln's executive order expressed the federal intention to blockade the rebellious states, but the actual blockade was not effective until the summer came and the ships were in place. From what I have read a blockade must be made actual to have legal standing. A declared blockade may serve as a pretext for war or rebellion, but it's not an act of war or an accepted cause for war. That at any rate is what I have been able to figure out.

Lincoln's call for volunteers (an echo of the earlier call by Davis) probably played a far greater role in provoking secession votes, especially in Tennessee and Arkansas.

Of course Lincoln and the federal government could have proceded differently. This seems to be one of the hot topics in current Civil War writing. Some have argued that, by acting differently, Lincoln could have kept the Upper South in the Union. It's an interesting question, but it's worth remembering that there were other actors and forces at work. Lincoln was as much reacting as acting, particularly after Sumter.

The Confederates, too, were doing all they could to win over in the Upper South and the Border States. The prospect of provoking secession in Virginia and the other Border and Upper South states was likely in Davis's mind when he ordered the firing on Sumter that sparked the war (to the extent that he wasn't trying to act for the Confederacy before South Carolina acted on its own).