Thus far, the only technique that had shown promise was skip-bombing. Unfortunately, the characteristics that made the B-17 ideal for long-range attack-namely their tremendous range and payload-did not translate favorably for skip-bombing in broad daylight. The sheer size, lack of maneuverability, and relatively low speed of the heavy bombers made them too vulnerable at low level. The same was not true of smaller, twin-engine aircraft. In late 1942, thanks to a combination of happenstance and ingenuity, two U.S. Army models underwent modifications that changed the course of attack aviation. The first of these, the Douglas A-20 Havoc light bomber, began its evolution by default. When the 89th Bomb Squadron/3rd Bomb group received its first A-20’s at Charters Towers in August 1942, the aircraft were supposed to be equipped with four fixed, .30 caliber machine guns in fuselage blisters and three additional machine guns in flexible mounts. But the guns had not been installed, and to make matters worse, the A-20’s fuel capacity allowed a combat radius of only 250 miles. There were few Japanese targets within that distance, even when staging from Port Moresby. Seeking improvements, the 3rd Bomb Group turned to a middle-aged engineering officer who had joined them earlier that year under unusual circumstances. One of the most innovative men in the Fifth Air Force, forty-three –year-old Major Paul I. “Pappy” Gunn had worked his way out of an impoverished youth in the Ozark Mountains. Blessed with an innate ability to understand anything mechanical, Gunn trained as an aviation mechanic in the U.S. Navy and later earned his wings as an enlisted pilot. Retiring as a chief petty officer after a twenty-year career, he became the operations manager and chief pilot for the Philippine Air Lines in 1939. When the Japanese attacked two years later, the U.S. Army Air Corps commandeered his planes and commissioned him as a captain. Soon thereafter, Manila fell, but Gunn was out of the country to transport a planeload of aviators to Australia. His wife and four children became prisoners, giving him the incentive to wage a private war against the Japanese. Stuck for all practical purposes in Australia, Gunn was well-acquainted with “Big Jim” Davies and attached himself to the 3rd Bomb Group at Charters Towers. Gunn was renowned, as we would now put it, for “thinking outside the box.” Perhaps more than any other individual in the Southwest Pacific, he possessed the raw genius to conceptualize an entirely different roll for the A-20 than its designer had intended. Gunn discarded the notion of using the A-20 as a conventional bomber and envisioned a low-level attacker, primarily a gunship, which negated the need for a bombardier. By eliminating that position and all of the associated equipment, plenty of space became available in the nose of the aircraft for mounting four fixed .50-caliber machine guns. Gunn replaced the .30-caliber guns in the fuselage blisters with a single .50-caliber machine gun on each side, giving the A-20 a total of six forward-firing heavy machine guns. And with the power turret behind the cockpit locked forward, two more “fifties” were available. The bomber’s combat range was increased by installing two fuel tanks totaling nine hundred extra gallons in the forward bomb bay, and honeycomb racks mounted in the rear compartment enabled the A-20 to carry forty or more small parafrag bombs. Gunn personally conducted much of the flight-testing to ensure that important factors such as center of gravity (a critical component of safe flight) and structural integrity had not been compromised. The changes were true field modifications, done completely outside normal channels without the hindrance of bureaucratic red tape. In a remarkably short time, the A-20’s were transformed into potent attackers.