Final answer:
The story of Rain Reign begins in the month of October according to the main character, Rose.
Step-by-step explanation:
The story of Rain Reign begins in October, as indicated by the main character, Rose.
This month is not only significant as the time when the narrative starts but also holds importance as it leads to remarkable events in her life involving her dog, Rain. The historical moment mentioned does not appear in the references provided, as they seem to be from different literary sources that focus on themes of love, war, and the quest for a red rose, rather than the plot details of Rain Reign.