The War was not caused by Secession

I will demonstrate this by way of the chronology of events.

Dec 24, 1860 - South Carolina secedes from the Union. Followed within two months by Mississippi, Florida, Alabama, Georgia, Louisiana and Texas.

Seven independent states and no confederacy as yet.

April 12, 1861, South Carolina fires on Ft. Sumter.

One independent nation, per its declaration, fires on a federal fort.

April 15, 1861 - President Lincoln issues a Proclamation calling for 75,000 militiamen, and summoning a special session of Congress for July 4

Here we have a prelimary to war but no specific enemy as yet.

April 17, 1861 - Virginia secedes from the Union. Followed within five weeks by North Carolina, Tennessee and Arkansas.

Note followed within five weeks.

April 19, 1861 - The president issues a Proclaimation of Blockade against Southern ports.

But two days laters when only eight states have seceded, all southern states are blockaded.

April 29, 1861 - The Constitution of the Confederate States of American ratified.

And ten days after that blockade is ordered, there is for the first time a nation to treat as a unit. One has to wonder what the blockade contributed to its ratification.
So for the shooting actions of one idependent nation, not because it was an independent nation, not because it had seceeded, Lincoln blockaded nine nations.

The war is clearly not related to secession as seven states had left the US for months before the shooting started. And the event that starts the shooting, while related to secession, is not over secession itself.

And Lincoln took the actions of one state as a pretext to blockade (and a blockade is an act of war) seven independent states that had not participated in that action. Lincoln's war anyone?