While imprisoned , Nicholson was asked to be an independent witness that the Germans did not perpetrate the Katyn massacre , where around 20,000 Polish officers and intelligentsia were killed by the Soviets . Nicholson , the senior British officer at his camp , and the senior American officer , Col. John H. Van Vliet ( later the author of the " Van Vliet report " implicating the Soviets in the massacre ) refused , not wanting to be part of a German propaganda effort . Van Vliet and another American officer were later forced to go
Katyn massacre
Katyn massacre
Claude Nicholson (British Army officer)