Final answer:
When Victor was 17, he witnessed the historic assassination of Archduke Franz Ferdinand which sparked World War I, and the aftermath of the war that led to societal and political transformations.
Step-by-step explanation:
When Victor was 17, two significant historical events took place that would shape the course of the 20th century. The first was the assassination of Archduke Franz Ferdinand and his wife Sophie by Gavrillo Princip on June 28, 1914. This event is widely regarded as the spark that ignited World War I, setting off a series of alliances and conflicts that engaged numerous countries around the globe. The second event, although not specified in Victor's context, could refer to the wide-ranging effects of World War I on societies, including the profound social and political changes that led to the emergence of a 'lost generation' deeply affected by the war's devastation. These events marked a departure from traditional norms and heralded significant changes in global relations and national identities.