During the Battle of the Marianas, the D4Ys were engaged by U.S. Navy fighters and shot down in large numbers. It was faster than the Grumman F4F Wildcat, but not the new Grumman F6F Hellcat which entered combat in September 1943. The Japanese aircraft were adequate for 1943, but the rapid advances in American materiel in 1944 (among them, the introduction in large numbers of the "Essex"-class aircraft carrier) left the Japanese behind. Another disadvantage suffered by the Japanese was their inexperienced pilots.