The king was then at Narbonne, on his way to his army, which was besieging Perpignan.  The grand equerry was with him.  Fontrailles went to call upon him.  “I do not intend to be seen by anybody,” said he, “but to make speedily for England, as I do not think I am strong enough to undergo the torture the cardinal might put me to in his own room on the least suspicion.”  On the 21st of April, the cardinal was dangerously ill, and the king left him at Narbonne a prey to violent fever, with an abscess on the arm which prevented him from writing, whilst Cinq-Mars, ever present and ever at work, was doing his best to insinuate into his master’s mind suspicion of the minister, and the hopes founded upon his disgrace or death.  The king listened, as he subsequently avowed, in order to discover his favorite’s wicked thoughts and make him tell all he had in his heart.  “The king was tacitly the head of this conspiracy,” says Madame de Motteville:  “the grand equerry was the soul of it; the name made use of was that of the Duke of Orleans, the king’s only brother; and their counsel was the Duke of Bouillon, who joined with them because, having belonged to the party of M. de Soissons, he was in very ill odor at court.  They all formed fine projects touching the change that was to take place to the advantage of their aggrandizement and fortunes, persuading themselves that the cardinal could not live above a few days, during which he would not be able to set himself right with the king.”  Such were their projects and their hopes when the Gazette de France, on the 21st of June, 1642, gave these two pieces of news both together.  “The cardinal-duke, after remaining two days at Arles, embarked on the 11th of this month for Tarascon, his health becoming better and better.  The king has ordered under arrest Marquis de Cinq-Mars, grand equerry of France.”

Great was the surprise, and still greater was the dismay, amongst the friends of Cinq-Mars.  “Your grand designs are as well known at Paris as that the Seine flows under the Pont Neuf,” wrote Mary di Gonzaga to him a few days previously.

Those grand designs so imprudently divulged caused a presentiment of great peril.  When left alone with his young favorite, and suddenly overwhelmed, amidst his army, with cares and business of which his minister usually relieved him, the king had too much wit not to perceive the frivolous insignificance of Cinq-Mars compared with the mighty capability of the cardinal.  “I love you more than ever,” he wrote to Richelieu:  “we have been too long together to be ever separated, as I wish everybody to understand.  In reply, the cardinal had sent him a copy of the treaty between Cinq-Mars and Spain.