In the study of history, which is unchanging over time?

s the president shall be commander in chief of the army and navy of the united states, and of the militia of the several states, when called into the actual service of the united states; he may require the opinion, in writing, of the principal officer in each of the executive departments. sooo yeahhh

explanation:

lincoln won 212 electoral votes to mcclellan's 21 votes, and lincoln beat mcclellan. is the main reason lincoln won in 1864.