[lentulusgracchus]

From 1861 to the summer of 1864 his status was U.S. citizen.

No, he wasn't. Virginia left the Union on May 23, 1861, and by secession, all citizens of Virginia, of whom Lee was one, ceased to be citizens of the United States.

[Non-Sequitur]

No, he wasn't. Virginia left the Union on May 23, 1861, and by secession, all citizens of Virginia, of whom Lee was one, ceased to be citizens of the United States.

He was, at best, a dual citizen. But the fact is that there was no confederate states to grant him citizenship.