Castle of Fort Ritchie, Military Intelligence Training Center during WWII, in Washington County, Maryland
During the WWII, there were ~700 POW camps in the nation. Among them, three camps were particularly important. Those three were operated to collect special military strategic or technical information through interrogation process.
In 1942, two intelligence information collection camps were started in the East (VA) & West (CA). The interrogation process was slower than originally anticipated. Therefore, the 3rd camp was opened in Pennsylvania in 1943.
As the top-secret project, all three camps were officially not existed without address. The camp in VA was called, P.O. Box 1142. Some of POWs did not know where they were. When they asked where they were in Canada or in US, the answer was, at P.O. Box 1142.
In order to collect intelligence information, interrogators were recruited. Many interrogators were German or other foreign language speaking immigrants, came to US in young age.
Fort Ritchie, originally Ritchie Camp was established as a summer training camp by the Maryland National Guard in 1926 and lasted until 1942.
Then, the US Army activated the Military Intelligence Training Center (MITC) on June 19, 1942 for training intelligence troops, including the Ritchie Boys, who were trained in methods of intelligence information collection skills as an interrogator.