 His talents commended him to the notice of Advocate Johan van Oldenbarnevelt, who sent him, at the age of 26 years, as a diplomatic agent of the states-general to the court of France.He took a considerable part in the negotiations of the Twelve Years' Truce in 1609.His conduct of affairs having displeased the French king, he was recalled from his post by Oldenbarneveldt in 1614, after the French ambassador Benjamin Aubery du Maurier had demanded Aarsens recall.