On May 21, 1989, the U.S. ambassador to China sent a chilling report to Washington: Troops were said to be advancing on Beijing; a power struggle was underway at the highest levels of the regime. “A confrontation resulting in bloodshed is probable,” came the warning. White House officials feared full-scale civil war. A few months later, in the city of Leipzig, in East Germany, 100,000 protesters faced armed security forces; hospitals were told to expect casualties. “It is not hard to imagine all that might have occurred had someone pulled a trigger that night,” says historian Jeffrey Engel. “Wars had started over less.” In Moscow, Mikhail Gorbachev wondered whether the reforms he had set in motion were cascading into a violent breakup of the Soviet Empire. And at every turn, President George H.W. Bush considered his limited options and the dangerous possibilities. Not one but two major global powers appeared to be coming apart at the seams.