Complex sentence: Angry that the Soviets had betrayed all principles by signing an accord with Hitler, Baldwin promptly sought to have all Communists removed from the ACLU board; the Communist labor organizer, Elizabeth Gurley Flynn, was among those purged from the organization.
Split into simpler sentences: Angry that the Soviets had betrayed all principles by signing an accord with Hitler, Baldwin promptly sought to have all Communists removed from the ACLU board. The Communist labor organizer Elizabeth Gurley Flynn was among those purged from the organization.