The war was declared over - the end of major combat operations - in May 2003. Release procedures got under way immediately; reducing the population from 8,000 to just over 300, of course, requires fewer military police soldiers.
A lot of knowledge in any kind of an organization is what we call task knowledge. These are things that people who have been there a long time understand are important, but they may not know how to talk about them. It's often called the culture of the organization.