David Kahn has died

Borrow from your library before the waitlist is massive

Should use that Washington Post obit link instead since Schneier not really adding anything

His history book from 1967 had a great influence on the generation of people who have created the civilian cryptography during the seventies of the 20th century, leading to breakthroughs like the DES standard developed at IBM (1975 draft, 1977 final) based on the earlier work of Horst Feistel (1970) and the public key cryptography developed from 1976 to 1979 by Whitfield Diffie, Martin E. Hellman, Ralph Charles Merkle, Michael Oser Rabin and the RSA team.

Before that, good cryptography was a monopoly of the military and diplomatic parts of the governments (except that even many governments were not competent enough to distinguish good cryptography from bad cryptography).

Because his book was about the history of cryptography, its technical content was obsolete. However its importance consisted in the fact that many of its readers became interested in cryptography, so then they have studied all available sources and they have thought about improvements, eventually leading to new methods and algorithms, which became public, unlike the classified methods used by the government.

I got The Codebreakers when I saw it on sale. The parts on the history on cryptography are a fascinating read.