Because he had to decide between serving his country the United State A.K.A. the Union or serving his state of Virginia which sided with the Confederacy.
The firing at Fort Sumter marked the beginning of the Civil War.
Lincoln's call for volunteers, following the firing on Fort Sumter by Confederate artillery.
Federal troops would not vacate Ft. Sumter after SC declared secession.
Lincoln declaring that he would defend all Union-held garrisons. It was effectively a declaration of war.
With the firing of Confederate artillery on the island-garrison of Fort Sumter in Charleston Harbour in April 1861.
The firing at Fort Sumter marked the beginning of the Civil War.
By firing on the island garrison of Fort Sumter - officially 'federal property', but to the Confederates, part of South Carolina.
cameron
1861
Confederates.
The firing on Fort Sumter
It occurred on April 1861.
P.G.T. Beauregard
confederate soldier fire on union troops in fort sumter.
Fort Sumter
Confederate artillery firing from Charleston across the harbour.
Artillery firing from The Battery in Charleston.