Final answer:
Conze's attitude to war was likely influenced by the assassination of Archduke Franz Ferdinand in 1914, which served as the critical spark for World War I, and by the broader impacts of World War II, including the Holocaust.
Step-by-step explanation:
The event that shaped Conze's attitude to war more than any other is not specifically mentioned in the provided reference material. However, based on the historical context given, it is likely that a deep understanding of the assassination of Archduke Franz Ferdinand in 1914 and the subsequent series of events that led to the outbreak of World War I, including alliances, nationalism, and military expansionism, could have greatly influenced Conze's perspective. The assassination was a critical spark that ignited the war due to the complex web of alliances among European powers. Additionally, the general upheaval and atrocities of World War II, including the Holocaust and actions of Russian troops, likely compounded and shaped Conze's view on war.