John Hawkins at Right Wing News has posted an interesting list of the 100 greatest Americans. I have one name to add to his list: William F. Friedman.

Friedman is known as the godfather of modern U.S. cryptology. His team of brilliant codebreakers cracked Japan’s highest security codes prior to World War II.

As Roberta Wohlstetter noted in her landmark book, Pearl Harbor: Warning and Decision, the ability to read Japan’s diplomatic codes allowed American leaders to see

the most private communications between the Japanese government and its ambassadors in Washington, Berlin, Rome, Berne, Ankara, and other major Japanese embassies throughout the world. They saw the reports of Japanese military attaches and secret agents in Honolulu, Panama , the Philippines, and the major ports of the Americas. They knew in advance the diplomatic moves that Japan was contemplating and the sorts of information that her agents were collecting on American defense preparedness.

Building on Friedman’s pioneering work, Navy cryptologists stationed in Hawaii figured out that Japan was planning to attack Midway. As a result, Admiral Chester Nimitz (who is rightly included on Hawkins’ list) was able to divert his own forces to Midway, where he led U.S. forces to a crucial victory.

Friedman isn’t as well known as Nimitz–that’s the nature of codebreaking–but the codebreaker’s quiet, dogged, behind-the-scenes contribution to the American war effort was as significant as Nimitz’s, if not more so.