Almost 90 US B-29 bombers dropped about 6,000 tons of napalm on Kumagaya, Japan, on the night of August 14-15, 1945. Eighty years later, the scars of that American firebombing remain.

What if history had taken a darker turn and the Soviet Union had allied with Nazi Germany in World War II? In this final part of the series, we explore whether the development and use of nuclear ...