Nov. 23—Abraham Lincoln established the national holiday of Thanksgiving in 1863, in the midst of the bloodiest conflict in American history. Yet he maintained there was so much for which to give thanks to the Creator. And a central message was, as he put it, that the great trial of a civil war, in God’s eyes, could bring forth the animation and inspiration of our hearts and minds to do what we had to do, even if we weren’t sure we were capable.