Why does Umuofia almost go to war with Mbaino in things fall apart?

The 2 villages are never almost at war. Umuofia's sending of a emissary in order to deal with the killing of a Umuofian clanswoman in the marketplace of Mbaino helps settle the issue, as Mbaino acknowledges that they were At Fault, agreeing to compensate Umuofia.