Today Mandiant is one of the most well known companies (well, now "brand" inside FireEye I guess) in cyber security and even the larger business world (when you get hacked badly, "Who you gonna call?"). Part of Mandiant's early cachet came from the fact that so many key personnel cut their cyber teeth within the Air Force. They had real world experience battling attackers aggressively going after military targets.
But 20 years ago in 1995 another group of Air Force expats formed one of the earliest commercial intrusion detection companies - WheelGroup.
WheelGroup, as co-founder Lee Sutterfield would pitch to me, wanted to be the ADT of the Internet. A few years later WheelGroup was acquired by Cisco. Interestingly, in 2014 Cisco launched Cisco Managed Threat Defense Service that is very similar to WheelGroup's original vision.
Here is a one of WheelGroup's slick sheets promoting their product/service. I encourage you to take a look at it to get a feel for what the the intrusion detection space was like 18 years ago.