You say you will not fight to free negroes. Some of them seem willing to fight for you; but, no matter. Fight you, then, exclusively to save the Union. I issued the proclamation on purpose to aid you in saving the Union. Whenever you shall have conquered all resistance to the Union, if I shall urge you to continue fighting, it will be an apt time, then, for you to declare you will not fight to free negroes.

Letter to James C. Conkling (1863)