Preparatory to this operation, Count Mathieu Dumas and the two brothers Berthier, with several other young officers attached to the French staff, who had for some days been zealously engaged in exploring the ground and roads, and in sketching maps of the country, between the allied Camp and Kingsbridge, were ordered by the French commander to set out before day-light, and to push their examinations till they came within sight of the enemy's most advanced re-doubts at the northern extremity of New York Island. To protect these youthful aspirants for martial honors, a strong detachment of the lancers of Lauzun was sent along, under Lieutenant Charles Jennings Kilmaine, a young Irishman in the French service, whose merits were just then becoming known, and who afterward became a general of division and enjoyed the reputation of being one of the best cavalry offi-cers in Europe. The command of the whole party was bestowed upon Dumas. Cornelius Oakley was selected upon this occasion, to act as the principal guide, accompan-ied by his cousin James and by Andrew Corsa. Near Milesquare, Kilmaine fell in with a patrol of refugees which he charged and dispersed. Further down, the recon-noitring party was formed a junction with a select body of Amer-ican light-infantry, who the same morning, had gone down to explore the ground on the right, and the two allied detach-ments then drove across Kingsbridge the troops that occu-pied the Hessian outpost; pursuing the fugitives, till they came within musket shot of Prince Charles' redoubt. This reconnaissance was the first occasion upon which Kilmaine particularly distinguished himself, and it established in favor of the elder Berthier, a reputation for intrepidity which led to his promotion. While at some distance from his com-rades, the latter fell in with, and was attacked by one of Colonel James Delancey's corps of refugees.