He was a member of the English aristocracy, and after the French Revolution of 1789, which overthrew the French aristocracy, he saw the imprisonment and execution of hundreds of members of the French aristocracy. The aristocracies of the two countries were closely linked and sympathetic to each other (often intermarried), and Percy decided he needed to save those who otherwise would have been subject to the brutal executions carried out by Robespierre. He assembled a group of fellow English nobility to enter France and rescue the French nobility facing death. He personally did so in disguise, so no one knew his identity (hence the name "The Scarlet Pimpernel"). In the book he took particular delight in carrying away condemned prisoners from right under the nose of the revolutionary forces. At that time in history, there was still hope that the revolution would founder and the French aristocracy would return to the throne, so part of the strategy was to protect the royal lineage and prepare the for a return. The novel was actually written in 1922, when such ideas of course were no longer being considered, but coming after the Great War and at a time when fantasy and romance were an important part of popular entertainment, this kind of story appealed to readers from a new perspective.