Over the following twenty years, Whitehead participated in Billy Mitchell's aerial bombing demonstration and served as commander of the 94th and 36th Pursuit Squadrons among other assignments.On July 20, 1921, he participated in Brigadier General Billy Mitchell's demonstration bombing attack of the ex-German dreadnought Ostfriesland.[10] In December 1926, Whitehead was assigned as the co-pilot for Major Herbert A. Dargue, leading the 22,000-mile (35,000 km) Pan American Good Will Flight touring South America.During a landing at Buenos Aires in March 1927, their aircraft, a Loening OA-1A float plane nicknamed New York, was involved in a mid-air collision with the Detroit, another OA-1A, forcing both Dargue and Whitehead to bail out.[11] The remaining four planes of the flight completed the tour, for which all ten airmen including Whitehead received the first awards of the Distinguished Flying Cross.At the recent Battle of Milne Bay, a Japanese invasion force had managed to sail past all but a few RAAF P-40 Kittyhawk and Lockheed Hudson aircraft, suffering only limited damage.Opinion at MacArthur's General Headquarters (GHQ) was that "the failure of the Air in this situation is deplorable; it will encourage the enemy to attempt further landings, with the assurance of impunity".[20] Unable to provide MacArthur with what he most needed—more and better aircraft and the crews to man them—Arnold decided to replace Brett with Major General George C. Kenney.But Kenney realized that he would have to maintain his headquarters near MacArthur's GHQ, which moved to Brisbane on July 20, while the fighting was thousands of miles away in New Guinea, with the Fifth Air Force's principal forward bases around Port Moresby.New airfields were developed, along with roads, housing, taxiways and revetments to protect his aircraft from the frequent Japanese air raids.For a time, despite the efforts of his airmen and the ground troops, the Japanese advanced steadily on Port Moresby, but they ultimately turned back short of it.Skip bombing was a new tactic adopted by the Fifth Air Force that enabled its bombers to attack ships at low level.The parachute fragmentation (parafrag) bomb gave the light bombers increased accuracy for close air support missions.Although the B-25 Mitchell was originally designed to bomb from medium altitudes in level flight, Major Paul "Pappy" Gunn had additional guns installed in the nose of the aircraft to enable it to perform in a low-level strafing role.The battle caused the Japanese to abandon all further attempts to bring supplies and reinforcements in to Lae by the direct sea route from Rabaul."[30] As the Allied offensive gained steam, Whitehead's main task was to shift his aircraft forward, advancing the bomb line incrementally towards Japan.