 In practice , MacArthur controlled land operations through " task forces " . These reported directly to GHQ , and their commanders could control all Allied land , air , naval and service forces in their area if a Japanese land attack was imminent . The most important of these was New Guinea Force , which was formed in 1942 and was commanded personally by Blamey in September 1942 , and again in September 1943 . In February 1943 , Lieutenant General Walter Krueger 's Sixth Army arrived in SWPA , and its headquarters became that of Alamo Force . Alamo Force reported directly to MacArthur , and as a result Blamey did not command of the majority of American land forces in the theatre after that time , although his post was not abolished . 
