Reid, Mayne: The Boy Slaves v1 15 jan 2009
 

Thomas Mayne Reid (April 4, 1818 – October 22, 1883), was an Irish-American novelist. "Captain" Reid wrote many adventure novels akin to those written by Frederick Marryat and Robert Louis Stevenson. He was a great admirer of Lord Byron. These novels contain action that takes place primarily in untamed settings: the American West, Mexico, South Africa, the Himalayas, and Jamaica.(Wikipedia)

This one takes place in Ethiopia, of all places. Three young lads are kidnapped and enslaved, but succeed, in the end, to free themselves.

Some illustrations.
Have fun!