Half of a Yellow Sun by Chimamanda Ngozi Adichie

Review from NPR:

The book's title comes from the Biafran flag. Olana Ozobia is a well educated Igbo woman who does her part in the war effort by teaching a class in the small town in which she and her lover, a nationalist intellectual, and his infant love child, have been evacuated.

The half of a yellow sun stood for the glorious future. The present is not so glorious. The book mainly follows the fortunes of Olana and those of a fascinating and varied cast of characters, from high society colonials on down to Ojukwu, an Igbo country boy. Though their daily lives and destinies are tied to the end of peace and the rise of war, Adichie makes them, above all else, interesting, even compelling, as sharply defined individuals. This lends to the novel a powerful psychological element that we don't always find in historical fiction.