Louis XIII became king as a child after his father Henri IV's assassination. His marriage to Anne of Austria, daughter of Spain's king, was arranged by the Fontainebleau agreements to establish peace between France and Spain, ending their long-standing conflicts.

He governed predominantly through advisors, chiefly Cardinal Richelieu, whom he appointed to reinforce royal power during regional disputes. Preferring courtly diversions over governance, Louis XIII delegated daily administration, enabling figures like Richelieu and Milady de Winter to orchestrate political schemes—including plots against Queen Anne—while internal threats emerged from his ministers. Despite this, he upheld the crown's ultimate authority.

A pivotal crisis unfolded when his twin brother Philippe, aided by Milady and the Man in the Iron Mask, usurped the throne through conspiracy. The true king was imprisoned with an irremovable iron mask, falsely branded as the villainous Iron Mask while awaiting execution. Philippe's impersonation saw allies like Richelieu and Anne imprisoned, and musketeers disbanded or turned traitor, marking Louis XIII's complete loss of identity and power.

Initially adversaries Athos and Rochefort allied to attempt his escape but were captured. Jean, an orphan aligned with d'Artagnan, discovered their prepared weakened cell wall, enabling the king's rescue. United efforts of musketeers, Cardinal Guards, and allies restored Louis XIII to the throne after confronting the impostor and conspirators. Kingdom stability returned with the conspirators neutralized.