As the Japanese regrouped west of the Matanikau, the U.S. forces concentrated on shoring up and strengthening their Lunga defenses. On 14 September Vandegrift moved another battalion, the 3rd Battalion, 2nd Marine Regiment (3/2), from Tulagi to Guadalcanal. On 18 September an Allied naval convoy delivered 4,157 men from the 3rd Provisional Marine Brigade (the 7th Marine Regiment plus a battalion from the 11th Marine Regiment and some additional support units), 137 vehicles, tents, aviation fuel, ammunition, rations, and engineering equipment to Guadalcanal. These crucial reinforcements allowed Vandegrift, beginning on 19 September, to establish an unbroken line of defense around the Lunga perimeter. While covering this convoy the aircraft carrier was scuttled after being hit by torpedoes from the Japanese submarine southeast of Guadalcanal. This left only one Allied aircraft carrier () in operation in the South Pacific area. Vandegrift also made some changes in the senior leadership of his combat units, transferring off the island several officers who did not meet his performance standards and promoting junior officers who had proven themselves to take their place. One of these was the recently promoted Colonel Merritt Edson, who was placed in command of the 5th Marine Regiment.