When you think of the great missionaries of the past, add another to your list: William Haas. 

He did the impossible, compelled by a burden that the unreached people of central Africa must have the gospel. His astounding sacrifices—and those of his wife, Genevieve—transformed the Central African Republic and spread the gospel across the world. 

Read his story in the book The Reward Unseen available in print, e-book, or audio at resources.bmm.org