The House Un-American Activities Committee was created to investigate whether communist and fascist organizations had in fact become active during the Great Depression within the United States.
It was clear that this committee's actions divided the 2 political parties, one was on the side of the committee that claimed that they discovered communist activities within the US without much evidence. While the other party claimed that the committee was formed to discredit President Roosevelt's "New Deal".
It impacted history at the time because it divided the two political parties. When at the time "The Great Depression", we should have come together as one nation in order to over come the current economic situation within the United States.