On September 11, 2012 Ambassabor Chris Stevens and others were killed in a terrorist attack on the Consulate in Benghazi. We speculated if Mrs. Clinton had talked about details of the movements of the people on the ground in Benghazi in her unsecure email system, the terrorists would have used this for targeting and may have enabled the terrorist to bring about their attack.
While we do not yet have access to all of her emails, Breitbart has published some excerpts from emails regarding the movements of Christopher Stevens.
This was devastating. Let me explain:
Put yourself in the shoes of a terrorist who is planning an attack. The usual things, weapons, logistics, etc. are already taken care of, since you are operating on home turf. To complete the plan you need information about where the target will be, when and for how long he will be there, and what are his security arrangements. Thanks to Hillary's emails, you now have access. Make your plan, execute your plan, your targets are dead, all your people are alive and free. Yes, the right intelligence is that valuable.
If Consulate security is run competently, terrorist attacks and/or ambushes are very difficult, because the target (in this case Ambassador Stevens) moves quickly, vulnerabilities are hardened and security assets have the advantage of knowing their methods and where they are going, and the terrorists do shris.
The emails provided advanced information on where the Ambassador would be and his plans and intentions. Not only does this provide specific targeting information in the short term, but it also enables the terrorists to watch security arrangements being made before the Ambassador arrives, to study the security preparations and to devise attacks to circumvent them.
Equally important, it allows terrorist surveillance to be more secure. It is a huge advantage for terrorist team to dig in and establish static surveillance before security is in place. Static surveillance (i.e. an observation post so well camouflaged it can't be detected) ahead of time means security assets arriving on the scene and looking for movement or suspicious activity will not see it.