It was 1966, and the United States was at war again, this time in Southeast Asia, fighting Communists in South Vietnam. Our forces were also holding the line against the same foe in Europe and in faraway places such as Korea. My name is Bill Carpenter, and I was 24 years old. I had just graduated in March from Colorado State University, in Fort Collins, with a bachelor of science degree in wildlife management. Iā€™m originally from the hills of West Virginia, but my family moved to Denver after I graduated from high school.

After the defeat of Nazi Germany in 1945, the Potsdam Agreement stipulated that Berlin would be occupied by the four major allied powers of World War II: the Soviet Union, the United States, the UK, and France. But the warā€™s end seemed to herald an even graver danger: a world split into two hostile camps, both armed with nuclear missiles. The East, with the centrally planned economies of the Soviet Union and its Warsaw Pact allies, faced the West, with the democratic, market-driven economies of the United States and its NATO allies. Nowhere was this tense rivalry more starkly depicted than in the divided city of Berlin, deep inside Communist East Germany.