For all the attention to Lincoln’s ideas and motivations, however, there has been very little focus on the delegates’ side of the story. For decades no one even knew who they were, much less what they stood for. Drawing on the work of the historian Benjamin Quarles, many believed that four of the five delegates were uneducated former slaves, hand-picked by Lincoln and his colonization commissioner, James Mitchell, to be pliable and subservient. In fact, all five of the men who listened to Lincoln’s case for colonization were members of Washington’s free black elite, chosen...