Adding temporal depth, Chapter 8 evaluates the influence of past golden ages on nationalist claims and conflict. It extends Chapter 7’s analysis of the nexus between nationalism and conflict by adding temporal depth and assessing whether restorative nationalism increases the risk of conflict. Taking nationalist narratives seriously, we study how the wish to restore past golden ages can be used to legitimize territorial claims and mobilize resources for action, as it did for the Polish nationalists who repeatedly rebelled against Russian occupation throughout the nineteenth century. The goal is to reconstruct plausible golden ages by combining ethnic settlement data with information on European state borders going back to 1100 CE. The analysis shows that the availability of a plausible golden age during which a group enjoyed political independence increases the risk of both domestic and interstate conflict. These findings suggest that specific historical legacies make some modern nationalisms more consequential than others, an interpretation that challenges radically modernist takes on nationalist mobilization.