The Last Prince of the Mexican Empire

From the publishers:
Who knew that Mexico once had a half-American prince? Or that this little boy's future was hotly debated not just in Mexico but in Washington D.C. and in every court in Europe? Set in the mid-19th century when Maximilian von Habsburg was Emperor of Mexico, The Last Prince of the Mexican Empire is based on the true and never before completely told story about the little boy who, as in a fairytale, became a prince— and a pawn in the struggle-to-the-death over Mexico's destiny. A fairytale based on the true but never before completely told story— the work of seven years of travel and research in archives as far flung as Vienna, Washington DC, and Mexico City— it begins, as it must, with, “Once upon a time…”
 
Excerpts from the book can be found here (external link).