The Dutchman not only insinuated himself into the confidence of the conspirators, but likewise inveigled Grandval to Eyndhoven, where he was apprehended.
Understanding that Dumont had already discovered the design to the duke of Zell, and that he himself had been betrayed by Leefdale, he freely confessed all the particulars without enduring the torture; and, being found guilty by a court-martial, was executed as a traitor.
About this period the duke of Leinster arrived at Ostend, with the troops which had been embarked at St.Helen's.

He was furnished with cannon sent down the Meuse from Maestricht, and reinforced by a large detachment from the king's camp at Gramont, under the command of general Ptolemache.

He took possession of Furnes, was joined by the earl of Portland and M.d'Auverquerque, and a disposition was made for investing Dunkirk; but on further deliberation the enterprise was thought very dangerous, and therefore laid aside.

Furnes and Dixmuyde, lately reduced by brigadier Ramsay, were strengthened with new works, and secured by strong garrisons.

The cannon were sent back, and the troops returning to Ostend, re-embarked for England.