In company with members of the 15th Company of Marines, all mounted, 1st Lt. Ostermann left Fort Liberte, Haiti, for a 6-day reconnaissance. After dark on the evening of 24 October 1915, while crossing the river in a deep ravine, the detachment was suddenly fired upon from 3 sides by about 400 Cacos concealed in bushes about 100 yards from the fort. The marine detachment fought its way forward to a good position, which it maintained during the night, although subjected to a continuous fire from the Cacos. At daybreak, 1st Lt. Ostermann, in command of 1 of the 3 squads which advanced in 3 different directions, led his men forward, surprising and scattering the Cacos, and aiding in the capture of Fort Dipitie.