The engineer's view: The Iron Age, with iron, stonework, brasswork, woodworking, weaving, and agriculture, ran until the 1600s or so. Then there was a period of tinkering and one-offs, but not much happened until 1830.
Then, in 1830, the Liverpool and Manchester Railway opened. That was the moment when the industrial revolution got out of beta. The Liverpool and Manchester had passenger tickets, double track, schedules, and all steam locomotives - no horses, no cable hauling. (There's a great documentary for which I lack the link, for which replicas, or even the originals, of early locomotives were taken out and run. Everything before the Liverpool and Manchester was clunky and didn't run smoothly. The narrator rides the Liverpool and Manchester train, which is smoothly running at about 30MPH, and drinks from a glass.)
It's hard to overstate how much of advantage the computers in Bletchley Park gave the allies in WWII. At least bump the Computer Age back one year so you can get D-Day in there.
Bletchley Park did not have general-purpose computers as we understand them. They had special-purpose hardware key-testers - the electromechanical bombe, and the electronic Colossus. Their successor today is a Bitcoin miner.
Although it gets less publicity today, Friedman's cryptanalysis operation in the US did much more number-crunching. Friedman turned cryptanalysis from guessing and testing into a statistical problem.[1] He and his organizations made heavy use of modified IBM tabulators during WWII.[2] Those were much more general purpose machines, somewhat programmable.
It seems to me that “military history” in this case is like a 30-year preview of the Computer Age: maybe I’m just young, but I’d generally put the start of the Computer Age around the time of the invention of FORTRAN and Lisp. To my mind, everything before was a “beta”.
Huh, I was expecting a discussion of a language problem about how you take historical texts from the early days and add punctuation to it. I know things can be "period"-ized different ways because I've read Bibles where the there's new verse numbers starting in the middle of a sentence.
Dividing history into epochs seems like a much more intractable problem, because the future was already then, it was just unevenly distributed. Taking the names to be more meaningful than conventions is a little silly.
My high school history books always used watershed moments. The beginning of a chapter was a big event, then some explanation of the fallout of the event, and then some context on the buildup to the next big event and then.... next chapter!
Then, in 1830, the Liverpool and Manchester Railway opened. That was the moment when the industrial revolution got out of beta. The Liverpool and Manchester had passenger tickets, double track, schedules, and all steam locomotives - no horses, no cable hauling. (There's a great documentary for which I lack the link, for which replicas, or even the originals, of early locomotives were taken out and run. Everything before the Liverpool and Manchester was clunky and didn't run smoothly. The narrator rides the Liverpool and Manchester train, which is smoothly running at about 30MPH, and drinks from a glass.)
And then the modern world began.