This book doesn’t really need explanation because the title says it all. The act and career of espionage spans the world. It began during the ancient times of Moses, Julius Caesar, and Sun Tzu and filters into Renaissance Europe with Marco Polo and Francis Walsingham. Turning to the early days of the United States, George Washington created a spy network that was instrumental to him winning the war against the British. On the other hand, Napoleon Bonaparte didn’t listen to his spies and resulted in a disaster in Russia. Back in the U.S. during the Civil War, both the Confederacy and Union had spies. At the turn of the century, both the World Wars had countless spies on many sides and Adolf Hitler almost won his war to conquer Europe. There were more behind the scenes in espionage as technology advanced and the Soviet Union became one of the countries to have a ruthless and spy network from the Cheka to NKVD to KGB to GRU and FSB. This led to the tension between the U.S. and Soviet Union during the Cold War where the CIA in the U.S. and KGB in Russia had undercover spies and double agents. The attack in New York City in 2001 and U.S. election interference in 2016 and 2020 led to more vigilance among the CIA, FBI, and NSA. There was valuable and insightful information and a quick read.