conducted an investigation
... that in 1941, a group of isolationist U.S. senators conducted an investigation into alleged "war propaganda" in Hollywood films?
... that in 1941, a group of <a href="./Isolationism" id="mwBUI" rel="mw:WikiLink" title="Isolationism">isolationist</a> U.S. senators <b id="mwBUM"><a href="./Senate_Investigation_into_Motion_Picture_War_Propaganda" id="mwBUQ" rel="mw:WikiLink" title="Senate Investigation into Motion Picture War Propaganda">conducted an investigation</a></b> into alleged "war propaganda" in Hollywood films?