Vincent was among the China Hands who wanted to gather intelligence from and provide material to the Communist armies, then part of the Allied coalition in the war against Japan and ostensibly under Chiang Kai-shek's command.
When Vincent and other China Hands including John Service accompanied Vice-President Henry A. Wallace on a state visit to the Soviet Union and Chongqing in June 1944, he helped to persuade Chiang to finally grant permission for the Dixie Mission, which opened contact with the Communist base areas.
According to the New York Times, The China experts, traveling through the areas controlled by various warlords, reported that Chiang's Nationalist Party, the Kuomintang, was dragging its feet, reserving its American-supplied arms for an eventual showdown with the Communists.
Vincent and the China Hands also argued that the Chinese Communists had their own genuine domestic roots that might trump any ideological loyalty to the USSR, as was occurring at the time with Tito's Yugoslavia.
[3] Dean Acheson, Truman's Secretary of State, steadfastly defended Vincent, just as he had done for Alger Hiss, and thought that the China Hands generally were being unfairly and demagogically maligned for honestly conveying inconvenient facts.