You may remember that Democrat President Andrew Johnson, from Eastern Tennissee, pardoned all remaining Confederates when he left office in 1869.
That ended any discussion about trying Davis for treason.
Davis then became a model citizen, urging reconciliation between South & North.
Lincoln wanted the war over with. And so did the American people on both sides. When Grant was leaving for Appomattox Lincoln said to him “Let them up easy’’. It was obvious he didn’t want further resentment and rebellion if he tried him for treason.
Tell truth Bro you’d of probably like to see Davis swinging rime the gallows, wouldn’t you? Lee too right?
Technically, a model "non-citizen". So, in effect, perhaps in retrospect, he, as an individual, did achieve personal and total secession from the USA. A man without a country.
A general amnesty was issued by Johnson but Davis was still under indictment. The Supreme Court just let it die without issuing a formal order of dismissal. Why didn’t they want a trial? Because the outcome would have been embarrassing for the federal government and the late disHonest Abe.