For thirty dramatic years, England ruled a great swath of France at the point of the sword an all-but-forgotten episode in the Hundred Years War that Juliet Barker brings to vivid life in "Conquest." Following Agincourt, Henry V s second invasion of France in 1417 launched a campaign that would place the crown of France on an English head. Buoyed by conquest, the English army seemed invincible. By the time of Henry s premature death in 1422, nearly...