Who is this person?

[Anita]

No Googling please.

Lincoln wrote in a letter,
"Without supposing that you and I are any nearer together, politically, than heretofore, allow me to tender you my sincere thanks for your Union resolution, expressive of views upon which we never were, and, I trust, never will be at variance. Yours very truly A. LINCOLN.

1. To whom was this letter written?
2. What was the reason for the "sincere thanks?
3. What was the date?