Only on the "CBS This Morning" podcast, author Kevin Peraino joins CBS News' Ann-Marie Green to discuss his book "A Force So Swift: Mao, Truman and the Birth of Modern China, 1949." They discuss how events unfolded and key leaders reacted when Nationalist China fell to Mao Zedong's Communist forces in 1949 -- an extraordinary political revolution that continues to shape East Asian politics to this day.