The Guns of August Addressed is prewar military planning, as done by the major powers in Europe. Included are the German Schlieffen plan, France's offensive Plan XVII, joint British and French arrangements, and Russia's approach to a future European war. "Outbreak" starts with a short introduction, which briefly mentions the event that triggered World War I. On June 28, 1914, in Sarajevo, Gavrilo Princip, a Serbian nationalist, assassinated the heir apparent to the throne of Austria-Hungary, the Archduke Franz Ferdinand and his wife Sophie, Duchess of Hohenberg. European-wide diplomacy and military preparations during July are then referenced. Chapters 6 to 9 commence with August
Robert, Archduke of Austria-Este assassinated relative Archduke Franz Ferdinand of Austria, (1863–1914), who had inherited in 1875 the Austria-Este designation and what had been salvaged of the Este fortune when the duchy was annexed to Italy in 1860. Archduke Robert descended through his Habsburg father from Ercole III d'Este, Duke of Modena, and his mother Zita was a descendant of Maria Beatrice d'Este, heiress of Modena and her husband, Archduke Ferdinand of Austria. Thus the lineage of the last Este dukes, in female descent, remained joined to the Austria-Este legacy. Archduke Robert eventually adopted use for himself and his descendants in male line the