Complex sentence: The Moratorium to End the War in Vietnam was a massive demonstration and teach-in against the United States involvement in the Vietnam War that took place across the United States on October 15,1969, followed a month later by a large Moratorium March on Washington.
Split into simpler sentences: The Moratorium to End the War in Vietnam was a massive demonstration and teach-in across the United States against the United States involvement in the Vietnam War. It took place on October 15,1969, followed a month later by a large Moratorium March on Washington.