In mid-August, "Northampton" sailed for the Southwest Pacific to join in the Guadalcanal operation. She patrolled southeast of San Cristobal, where on 15 September her force was attacked by submarines, which sank and damaged , and another torpedo hit badly damaged only off "Northampton"s port beam. Now sailing with "Hornet", "Northampton" screened the carrier during attacks on Bougainville Island on 5 October.