A half century of chronicling the history of World War II has largely overlooked a carefully cloaked world of dubious deals between American entrepreneurs and the Third Reich's financiers.

Newly declassified United States intelligence records reveal in unprecedented detail how US and Allied firms systematically used backwater countries to conduct backroom business with Axis enterprises. The files peel away a whole new layer of collaboration, describing scores of so-called ''shadow agreements'' in which corporations disguised their ties with the enemy through the cover of other companies in neutral countries, from Spain to Sweden to much of Latin America.

A 1943 chart drawn by the OSS shows the elaborate links between two German-run insurance companies -- La Internacional and El Feniz Sudamericano -- and a number of other firms, some of which were controlled by the Allies. Click to see larger version.

They show bank drafts and communiques moving among scores of shippers, banks, insurance companies, and exporters from nations at war. Global commerce was still conducted amidst global combat, and business blurred the boundaries between fascism and the free world.

This cloudy category of complicity is emerging only now, largely because of a somewhat chaotic dash to declassify ultra-sensitive espionage records in the United States, Western Europe, and the former Soviet bloc. The Nazi War Crimes Disclosure Act that Congress passed in 1998 has triggered the release of some 3 million pages of intelligence files, thereby helping to lift the last veil of secrecy on the US role in World War II.

Last year, the CIA released records of the virtually unknown Insurance Intelligence Unit, a component of the agency's wartime predecessor, the Office of Strategic Services. Besides supplying Allied battle planners with important target data, it also outlined the way insurance companies -- along with banking and shipping interests and governments of neutral countries -- conducted clandestine commerce that ignored lines drawn in blood on the battlefield.