Why did the men from Umuofia want to go to war with their neighboring tribe, Mbaino?
In Chapter Two, the Umuofia clan want to avenge the murder of Ogbuefi Udo's wife, who died at the hands of men from the Mbaino clan. The unfortunate woman was at the market in Mbaino when she was murdered.
After a meeting, the Umuofia clan immediately dispatches Okonkwo as an emissary to Mbaino. The goal is to threaten Mbaino with war if fitting compensation is not offered for the murder of the Umuofia woman. Because Umuofia has a fearsome reputation for prowess on the battlefield, Mbaino chooses to placate its formidable neighbor. A boy, Ikemefuna, and a young virgin are sent back with Okonkwo to Umuofia.
Accordingly, the young virgin becomes the wife of Ogbuefi Udo, and Ikemefuna is sent to live with Okonkwo until the clan decides his fate. Unbeknownst to Ikemefuna, his own father had participated in the murder of the Umuofia woman. Ikemefuna lives with Okonkwo for three years before the clan decides he must die for his father's guilt. Meanwhile, Ogbuefi Ezeudu, the oldest man in the clan, warns Okonkwo not to participate in Ikemefuna's death, but the formidable warrior ignores the warning, a decision he later regrets.