Military secrets from past wars

Factual Questions
1

As we all know, there are military secrets in practically all the wars that have been fought in history. A lot of these secrets deal with classified military technology and secret interceptions of enemy communications. What I’m curious about is when the “statute of limitations” on these secrets expires. In other words, I’m sure there’s plenty of information about the 2003 invasion of Iraq that’s still confidential, as well as the Gulf War in 1991. But how much farther back in time does one have to go before any and all confidential material about a particular war is considered safe enough to be released to the public?

For example, just a few years ago, the British government released classified military information from World Wars I and II. Is it possible that there’s more classified information still under wraps from those two wars? What possible military technology from 60 or more years ago could still be dangerous if released to the public? Wouldn’t it all be obsolete by now? Is there material from even older wars, such as the American Civil War, Franco-Prussian War, and even the American Revolutionary War that may still be classified? :confused:

2

Sixty years may seem like a huge amount of time and anything that old of historical interest only, but some secrets might still have a little life in them. Some young men who were recruited as spies back in 1945 are probably still alive, albeit retired. And the people they recruited during the course of their careers might still be active.

3

I think Little Nemo has the correct idea that information relating to secret agents and methods of gathering itelligence probably has the longest life. As to the physics and technology of weapons, once it is known that something can be done it usually doesn’t take too long to figure out how to do it.

4

Some secrets might be embarassing to the government or military.
Here’s a continuing story from WW2 involving the US keeping secrets:

5

There’s still a lot of classified stuff from World War II concerning cryptography. Not so much the messages that were decrypted, but the technical aspects of designing and breaking codes and ciphers.