While the Marines remained angry at the paucity of the overall preliminary naval bombardment of Iwo Jima, all hands valued the continuous and responsive support received from D-day onward. Many of the gunfire ships stood in close--frequently less than a mile offshore--to deliver along the flanks and front lines, and many took hits from masked Japanese coast defense batteries. There were literally no safe zones in or around the island. Two aspects of naval gunfire at Iwo Jima rate special mention. One was the extent to which the ships provided illumination rounds over the battlefield, especially during the early days before landing force artillery could assume the bulk of these missions. The second unique aspect was the degree of assistance provided by the smallest gunships, frequently modified landing craft armed with 4.2-inch mortars, rockets, or 20mm guns. These “small boys” proved invaluable, especially along the northwest coast where they frequently worked in lock-step with the 5th Marine Division as it approached The Gorge. While the Marines comprised the bulk of the landing force at Iwo Jima, they received early and increasing support from elements of the U.S. Army. Two of the four DUKW companies employed on D-day were Army units. The 138th Antiaircraft Artillery Group provided 90mm AA batteries around the newly captured airfields. Major General James E. Chaney, USA, who would become Island Commander, Iwo Jima, at the battle’s end, landed on D+8 with advance elements of the 145th Infantry. As far as the Marines on the ground were concerned, the most welcome Army units flew into Iwo Jima on 6 March (D+15). This was the 15th Fighter Group, the vanguard of VII Fighter Command destined to accompany the B-29s over Tokyo. The group included the 47th Fighter Squadron, a seasoned outfit of North American P-51 Mustangs. Although the Army pilots had no experience in direct air support of ground troops, Colonel Megee liked their “eager-beaver attitude” and willingness to learn. He also appreciated the fact that the Mustangs could deliver 1,000-pound bombs. Megee quickly trained the Army pilots in striking designated targets on nearby islands in response to a surface-based controller. In three days they were ready for Iwo Jima. Megee instructed the P-51 pilots to arm their bombs with 12-second delay fuzes, attack parallel to the front lines, and approach from a 45-degree angle. Sometimes these tactics produced spectacular results, especially along the west coast, where the big bombs with delayed fuzes blew the sides of entire cliffs into the ocean, exposing enemy caves and tunnels to direct fire from the sea. “The Air Force boys did a lot of good,” said Megee. With that, the escort carriers departed the area and left close air support to the 47th Fighter Squadron for the duration of the battle.