I love a good story, but before I decided to try writing Civil War History, I wrote three books on birds that were published by Barron's and I raised exotic birds for 17 years, and there's kind of a hole in this one.
If Abe was really taken from the best in 1861, then he would not have had his white head and tail until after the War. Bald Eagles are all dark until they turn 5 years old. He would have looked more like a large hawk than what you think of as looking like a bald eagle. So take the beginning part of the story, about him being taken from the nest by the Ojibwa people in 1861 with a grain of salt.