15 September 1628

15 September 1628 marks a decisive pivot in the narrative of The Three Musketeers, the moment when the king's restlessness and the cardinal's tactical indulgence combine to release the four friends from the trenches of La Rochelle and set them on a collision course with Milady at Bethune. The date is the fulcrum between the long, static siege and the swift, fatal journey that ends with Constance Bonacieux's poisoning and Milady's execution.

The King's Boredom and the Cardinal's Leave

By mid-September 1628, the siege of La Rochelle had dragged on for months. King Louis XIII, who was "bored, as always, but perhaps a little more so in camp than elsewhere," resolved to go incognito to St. Germain to spend the festival of St. Louis. He asked the cardinal to order him an escort of only twenty Musketeers. The cardinal, who "sometimes became weary of the king," granted this leave of absence with great pleasure to his royal lieutenant, who promised to return about the fifteenth of September. This seemingly casual arrangement was the mechanism that freed d'Artagnan, Athos, Porthos, and Aramis from their military duties at the very moment when their private mission—to rescue Constance from the convent at Bethune—had become urgent.

The Escort as a Strategic Opportunity

Monsieur de Treville, informed of the king's plan by the cardinal, immediately understood the imperative need his friends had to return to Paris. He fixed upon them to form part of the escort without knowing the full cause of their eagerness. The four young men heard the news a quarter of an hour after Treville himself, and d'Artagnan recognized that the cardinal's favor in making him a Musketeer had now become the condition of his departure—had he still been a Guardsman, he would have been forced to remain in the camp while his companions left. The escort thus became a cover for a private expedition, and the date of September 15 set the timetable for the race against Milady.

The Journey and the Fatal Encounter

The king, though anxious to be in Paris by the twenty-third, traveled slowly, stopping to fly the magpie, a pastime that exasperated d'Artagnan. The escort finally passed through Paris on the night of the twenty-third, and Treville granted the four friends furloughs that allowed them to set out for Bethune on the evening of the twenty-fourth. On the twenty-fifth, as they entered Arras, d'Artagnan recognized the Chevalier de Rochefort galloping past on a fresh horse, and a paper dropped from the stranger's hat bore the single word "Armentieres" in Milady's handwriting. This clue, discovered on the very day the king's leave had made their journey possible, led them directly to the isolated house on the Lys where they would try Milady and execute her.

The Aftermath: Return to the Siege

After the execution, the four friends returned to Paris within their leave of absence and paid their customary visit to Treville that same evening. The king, in compliance with his promise to the cardinal, returned to La Rochelle on the sixth of the following month. The date of September 15 thus stands as the hinge between the public war against the Huguenots and the private war against Milady—a moment when the machinery of state, driven by a monarch's ennui, inadvertently opened the path for the novel's climactic act of justice.