Attempts to show whether a set of watershed historical events occurring at a time are interlinked or overlap each other, sometimes by intent but often merely by happenstance, covering case studies such as the American expansion into the Pacific, the creation of the Soviet gulags in Siberia, and the end of the Vietnam War.

In 21 short case studies, this short book examines the distinctive coincidental history of America, Britain, and various Asian countries during the twentieth century. It covers a wide range of historical events, from American expansion into the Pacific to the creation of the Soviet gulags in Siberia to the end of the Vietnam War. Its main goal is to show how watershed historical events can often become layered or overlap each other, sometimes by intent but often merely by happenstance. As Ian Fleming once famously opined about actions in war: 'Once is happenstance. Twice is a coincidence. Three times is enemy action.'