Counterintelligence Corps

However, in the post-war period, the policy of isolationism, retrenchment of military spending, and economic depression meant that by the mid-1930s its numbers had fallen to fewer than 20 personnel.

On 13 December 1941, the Adjutant General of the Army issued an order renaming the CIP as the Counter Intelligence Corps, effective from 1 January 1942.

Special CIC teams were created during World War II in Europe, in large part from the Military Intelligence Service personnel (see Ritchie Boys).

One leading theory was expressed in the official history of the Corps, "the speed [of these events] left little doubt that someone—possibly Communists who still held key positions in government—was determined to halt CIC investigative activities in the United States".

[9] CIC units were also involved in providing security for the Manhattan Project, including duty as couriers of fissionable bomb materials from Los Alamos, New Mexico to Tinian.

They were also involved in providing security for military installations and staging areas, located enemy agents, and acted to counter stay-behind networks.

As the war in Europe came to a close, CIC were involved in the Operations Alsos, Paperclip and TICOM, searching for German personnel and research in atomic weapons, rockets and cryptography.

At the end of World War II CIC agents were successful in Operation Paperclip that obtained German rocket scientists for the United States before the Soviets took them.

After the war, in West Germany, the CIC also directed the so-called "Project Happiness" that sought to recruit former Gestapo and SD members as informants to infiltrate East German communist parties, such as the SED and KPD.

In the immediate post-war period, the CIC operated in the occupied countries, particularly Japan, Germany and Austria, countering the black market, and searching for and arresting notable members of the previous regime.

Despite the problem of demobilization, with many experienced agents returning to civilian life, CIC became the leading intelligence organization in the American occupation zones, and very soon found themselves facing a new enemy in the emerging Cold War.