Allied forces identified a Japanese airfield under construction at Guadalcanal, and 19,000 US Marines were embarked to capture the airfield. An amphibious landing was made on 7 August. The battle lasted until 9 February 1943 and was strongly contested, on land, at sea and in the air. Hyakutake's initial thrust on 14 September to re-take the island's Henderson Field was defeated. In an unequal battle, Major General Kiyotake Kawaguchi's forces lost about 850 killed, while the American Marines lost 104. When the news reached Imperial General Headquarters in Japan, they decided in an emergency session that they could not support fronts in both New Guinea and at Guadalcanal. Hyakutake decided that he only had sufficient troops and material to defeat the Allied forces on Guadalcanal. He prepared to send more troops to Guadalcanal in another attempt to recapture the airfield. With the concurrence of the Japanese command staff, he ordered Horii to withdraw his troops on the Kokoda Track until the issue at Guadalcanal was decided. The Japanese troops were, after several weeks of exhausting fighting and heavy losses, at Ioribaiwa, within of Port Moresby. There were also concerns that Allied forces might land at Buna at any time.