One of the major equipment changes for the campaign was the acquisition of 155mm guns as replacements for the older M1918 French Grande Puissance Filloux (GPF) guns. The battalion exchanged 90mm guns with the Army 70th Coast Artillery Battalion, giving the antiaircraft group new guns. High-speed and standard dual-mounts for 20mm guns were also obtained. These were adapted by the 9th from 37mm gun mounts, giving the light antiaircraft group greatly increased mobility by replacing the stationary naval single-mounts. The 9th Defense Battalion obtained additional .30-caliber heavy, water-cooled machine guns, and trained the battalion band to employ them with Headquarters and Service Battery. The battalion acquired three Landing Vehicle Tracked Alligator amphibious tractors for the operation, and then was augmented by a whole amphibious tractor platoon of nine vehicles from the 3d Marine Division. [Illustration: Marine Corps Historical Collection. _The antiaircraft group of the 9th Defense Battalion moves ashore at Rendova. Here a TD9 tractor pulls a 90mm gun from an LST. The TD9 tractor would soon prove too light to move through the muddy terrain beyond the beach._] On 27 June 1943, the battalion consisted of a total of 1,459 officers and men, reinforced with additional personnel from the 3d Marine Division and I Marine Amphibious Corps. Most of these Marines had been on Guadalcanal for seven months. At one time or another, 40 percent of them had malaria and the debilitating effects of the tropics had been felt by the entire unit. But the 9th was a well-trained, experienced unit, outfitted with the best equipment then available to Marine defense battalions. In the words of Lieutenant Colonel Scheyer, “the prospect of closing with the enemy was all that was needed to supply morale.” [Illustration: _The first Japanese aircraft shot down from the beach was credited to this gun crew on its first day ashore. From the left are 1stLt William A. Buckingham, PFC Francis W. O’Brien, Cpl Paul V. Duhamel, and PFC Nemo Hancock, Jr., of the 9th Defense Battalion._ Department of Defense Photo (USMC) 56812 ]