1942: Coral Sea, Port Moresby, Midway, Guadalcanal

In May 1942, the Allied navies in the Battle of the Coral Sea thwarted a Japanese naval attack on Port Moresby, New Guinea which had it succeeded would have put them within striking range of Australia. This was both the first successful opposition to Japanese plans and the first naval battle fought only between aircraft carriers. A month later the U.S. Navy again prevented the invasion of Midway Island, this time destroying four Japanese carriers, which Japanese industry could not replace, and putting the Japanese navy on the defensive.
However, in July the Japanese Army attempted an overland attack on Port Moresby, along the rugged Kokoda Track. Australian reservists, many of them very young and untrained, fought a stubborn rearguard action, until they were relieved by Australian regular troops returning from action in the Middle East.
The Allied leaders had agreed even prior to the American entry to the war that priority should be given to the defeat of Nazi Germany. Nonetheless US and Australian forces under General Douglas MacArthur began to attack captured territories, beginning with, against the bitter and determined defence of Japanese troops, Guadalcanal Island. On 7 August 1942 the island was assaulted by United States Marines. In late August and early September, while battle raged on Guadalcanal, Australian forces fought off a Japanese amphibious attack on the eastern tip of New Guinea at Milne Bay, the first conclusive defeat suffered by Japanese land forces. US forces triumphed on Guadalcanal in February 1943.