On 15 August 1684, the Sun King’s war against Emperor Leopold I and King Charles II of Spain reached a temporary end. Louis XIV had secured the advantage, and so several influential gentlemen sought to delight His Majesty with extravagant tributes. One of them was the Marquis de Seignelay, who spent the staggering sum of 100,000 livres on illuminations, lavish banquets, and a concert at his Château de Sceaux on a summer evening. In doing so, he sparked a sensation that echoed for years: the Idylle sur la Paix (Idyll on Peace), featuring music by the court composer Lully and poetry by the court poet Racine. The Duke of Richelieu (the great-nephew of the legendary Cardinal) could only remain in second place. He, too, had planned a grand fête at his estate, with music by Marc-Antoine Charpentier and the unveiling of an equestrian statue of the king. But the devil lurked in the details, and the Fête never came to pass. Now, 340 years later, the Boston Early Music Festival brings this long-lost vision to life.