[DiogenesLamp]

The first listed battle was relatively minor -- May 18, 1861 Confederate shore batteries in what was still officially Union Virginia fired on Union blockade gunboats in the Chesapeake Bay, near Norfolk.

And what part of the North is Norfolk in?

The first land battle was in Union West Virginia, at Philippi, June 3, 1861, a Union victory, about 30 total casualties.

And when did West Virginia become a State of the Union?

[BroJoeK]

DiogenesLamp: "And what part of the North is Norfolk in?"

At the time (May 18) it was still officially part of Union Virginia.
When Virginia voters ratified secession, on May 23, 1861, and joined the Confederacy's declared war on the United States, then the "international border" ran through the Chesapeake Bay off Norfolk.

DiogenesLamp: "And when did West Virginia become a State of the Union?"

At roughly the same time Virginia voters ratified secession, West Virginians voted to join the Union.