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.  Each of the short case studies focuses on one set of coincidental actions. Were they linked in some way? Or completely random? The reader is allowed to decide for themselves. Often, the coincidental overlap is due to timing, with various events throughout history occurring on the same dates. For example, Great Britain’s controversial blockade of Venezuela began on December 7, 1902, the U.S. Navy and the Royal Navy merged forces on December 7, 1917, and Japan attacked American and British naval bases on December 7, 1941. The author will suggest that these three actions were linked, but it is up to the reader to decide if it was really just a coincidence. The main goal of this short book 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.”