Final answer:
Churchill's Iron Curtain Speech in 1946 was significant for highlighting the East-West divide that became central to Cold War politics, symbolizing the barriers to freedom in the Soviet-controlled Eastern Europe, and spurring Western unity against communism which eventually led to the Cold War's end.
Step-by-step explanation:
The historical significance of the Iron Curtain Speech, given by Winston Churchill in 1946, lies in its role in defining the geopolitical and ideological divisions that would characterize the Cold War era. This speech illuminated the growing chasm between the democracies of Western Europe and the communist regimes of Eastern Europe dominated by the Soviet Union. Churchill's rhetoric emphasized the need for vigilance and cooperation among Western nations to counter the spread of communism.
Regarding the metaphor of the 'iron curtain', it was intended to signify a barrier meant to keep people in rather than keep people out—specifically, it referred to the Soviet Union's efforts to seal off its sphere of influence from the West and control the flow of information and people. The Iron Curtain symbolized the repression and lack of freedom in the Eastern bloc. Furthermore, the comparison to the 'Cotton Curtain' in America highlights other forms of systemic oppression, identifying issues with racism and inequality within the U.S. as well.
The fall of the Berlin Wall in 1989 marked the literal and symbolic dismantling of the Iron Curtain, leading to the end of Soviet dominance in Eastern Europe and eventually the demise of the Soviet Union itself, which marked the end of the Cold War.