In 1798, Irish patriots, committed to freeing their country from England, landed with a company of French troops in County Mayo, in westernmost Ireland. They were supposed to be an advance guard, followed by other French ships with the leader of the rebellion, Wolfe Tone. Briefly they triumphed, raising hopes among the impoverished local peasantry and gathering a group of supporters. But before long the insurgency collapsed in the face of a brutal...