I found that this particular image is the portrait of Eugenio Luis Juan Jose Napoleon IV Bonaparte (1856-1879). The reverse of the card indicates “Prince Imperial” which was his official title. Known as Louis-Napoleon, he was the only child of Napoleon III, Emperor of France and Empress Eugenie. The prince relocated with his family from France to England when his father was dethroned in 1870. He was only 14 at the time and eager to make his own name. As such, he served in the British Army during the Anglo-Zulu war in 1879, in which he was killed at the age of 23 in a rather rash and unwise venture into enemy territory without a full contingent of soldiers. His death ended the hopes of Imperialists who wished to return him to France and claim the throne as a 4th Bonaparte emperor. These prints were likely sold as souvenirs by the bookseller Maison Martinet.
Who Were They? 