Destiny of the Republic: A Tale of Madness, Medicine and the Murder of a President by Candice Millard
When you know perfectly well that the protagonist dies, and you still get teary eyed when it happens, that is a well told tale. It's not only that James Garfield was thoroughly likable, but my heart ached for his devoted wife and children, two of whom were with him when he was shot.
Destiny of the Republic is more than a biography of James Garfield. It is also an account of the life of his assassin, Charles Guiteau. Candice Millard manages to portray Guiteau with neither sympathy nor antipathy. Egotistical, and unlikable, he was clearly mentally ill.
However, it was not Guiteau's bullets that killed Garfield. Lingering for months after being shot, Garfield was ultimately killed by infection caused by the aggressive and unsanitary medical care he received at the hands of the egotistical Dr. Bliss.
Throughout, Millard places the story in the context of its day. The relationships between Garfield and those around him, the political climate and intrigues, the state of medical knowledge and practice, the technology of the day. She shows how Garfield's assassination and death led to changes in these various realms.