Ellis argued that with an enemy prepared to defend the beaches, success depended on high-speed movement of waves of assault craft, covered by heavy naval gunfire and attack from the air. He predicted that the decisive action would take place on the beach itself, so the assault teams would need not just infantry but also machine gun units, light artillery, light tanks, and combat engineers to defeat beach obstacles and defenses. Assuming the enemy had its own artillery, the landing craft would have to be specially built to protect the landing force. The failure at Gallipoli came because the Turks could easily reinforce the specific landing sites. The Japanese would be unable to land new forces on the islands under attack.