ZANGAR TOWN, Liberia — Joseph Duo edged his yellow taxi toward the river and boarded a canoe with stacks of grimy Liberian dollars and a backpack full of fliers promising more food, free education and better clinics. He marched down a damp muddy path, until the forest parted into a poor village named Zangar Town. His message was simple: Vote for me.

Fourteen years ago Mr. Duo did not cast the clean-cut, earnest image voters see today in his campaign posters, which are emblazoned with the word “Transformation.”

During the final throes of Liberia’s 14-year civil war, Mr. Duo was photographed jumping in the air: his torso bare and muscle-carved, his face stretched with excitement after he fired a rocket-propelled grenade at rebels. The picture, taken by the photographer Chris Hondros — who died in Misurata, Libya, in 2011 — became one of the defining images of a conflict that killed an estimated 250,000 people and displaced more than two million.