MacArthur proposed to move the first line of defense of Australia more than a thousand miles to the north, from Brisbane on the Tropic of Capricorn to the Owen Stanley mountain range in Papua, eastern New Guinea. This thrust also impelled US forces to defend Guadalcanal, whose conquest by Japan would have threatened a cutting of the sealane between Australia and the United States, which was MacArthur’s vital supply line. Another part of the incipient US-Australian offensive was the naval battle of the Coral Sea, in which a Japanese aircraft carrier was sunk and the aura of invincibility enjoyed by the Japanese fleet after Pearl Harbor shattered.
...snip ..
MacArthur was able to pursue his strategy with a great economy in the lives of his men. This was because he generally avoided frontal attacks in favor of the flanking envelopment. This allowed him to do more with less. The navy and marines just at Okinawa, for example, lost almost 50,000 men. MacArthur conquered New Guinea ... and the Philippines, going from Melbourne to Tokyo, with just 90,000 casualties. (By contrast, US losses at Anzio were 72,000, and in the battle of the Bulge, 107,000.)