Chadwick is compact, eulogistic, and informative; this is a great bit of expository writing without being only expository writing.
The plain story is how Chadwick and deciphered the written language of ancient Crete and Mycenae, partly by the logician's approach they practiced as codebreakers and mapmakers in WWII but partly by realizing that the spoken language might have been a form of Greek.
Chadwick doesn't explain why many Educated Men of his day were so surprised, even displeased, to find this precursor to Greek. The emotion that made sense all through was how sad he was to decipher these tablets, unread for thousands of years, and find them the prosaic arrangements for the failed defense of a civilization. Ventris died young too.
Chadwick, John. The Decipherment of Linear B. New York: Vintage Books, 1958.
So wrote clew in History.