..., under Capt. Gray, to capture the rebel pickets at Mackay's Point and at a plantation on the Pocotaligo River, a few miles distant. This project was only partially successful. At the plantation, Lieut. Banks , of the enemy's picket, and three men, were made prisoners, but through the incompetency of a negro guide, the guard at the point escaped, giving warning of our approach. From the rebel officer who...