Oddly, the Chicago Tribune revealed that the US won the Battle of Midway because we broke the Japanese naval code, but the Japanese missed or ignored it. The Japanese were complacent about US code breaking abilities because they regarded their codes as having innate extra security in that they saw their language as too difficult for enough foreigners to master so as to equip an effective enemy code breaking enterprise.
We really had that last with the Navaho code talkers and other groups.