Spying has always been part of great power conflict. Egyptians chiseled the oldest surviving intelligence reports on clay tablets 3,000 years ago. Even spy-themed entertainment has deep roots. Americans have Homeland. The Greeks had Homer. And yet, for centuries, nearly every aspect of the intelligence enterprise—the recruitment of spies, the making and breaking of encrypted messages, covert operations, analysis, and the inner workings of secret bureaucracies—has lurked in the background of historical studies. Espionage may be as old as history, but standard historical accounts often forget its significance. In international politics, intelligence is both powerful and invisible, pervasive and impenetrable.

Christopher Andrew’s The Secret World seeks to bring intelligence into the foreground of history where it belongs. To say that the book is ambitious understates. Covering three millennia across four continents in nearly 800 pages, Andrew aspires to write the first global history of intelligence. A global history of anything spanning 3,000 years has its challenges, and intelligence has more than most, for a very simple reason: Spymasters and politicians prefer that their secrets stay secret. Inevitably, then, the historical record is distorted by variations in governments’ abilities to record their shadowy deeds and their willingness to reveal them over time. Many Cold War histories, for example, discuss American covert operations in Cuba, Iran, Chile, and elsewhere but omit Soviet “active measures” around the world. This is not because the Soviet Union never conducted covert operations but because it was better able to keep them secret. During the Church Committee investigation of the 1970s, the CIA had to answer demands for greater transparency and accountability in a democratic system, something the KGB never had to do. It wasn’t until the Soviet Union collapsed and a former KGB archivist named Vasili Mitrokhin defected to Britain with trunkloads of records he had buried under his dacha that it became clear the KGB had played an even more active global role than the CIA did throughout the Cold War.

These challenges aside, Andrew is uniquely positioned for the mission. An emeritus professor of history at Cambridge University, he has written extensively about the history of intelligence in the Soviet Union, Great Britain, and the United States and served formerly as the Official Historian of Britain’s MI5. He also founded the Cambridge Intelligence Seminar, which for 20 years has gathered international intelligence scholars and practitioners.

The Secret World is a work of magisterial breadth. Andrew starts by examining the portrayal of spies in the Bible. “The first major figure in world literature to emphasize the importance of good intelligence is God,” he wryly notes. The book proceeds in rough chronological order, offering intelligence highlights across geographies that center on four recurring topics: the role of human intelligence (old fashioned spies), signals intelligence (the making and breaking of coded communications), covert operations (mostly involving assassination plots of foreign leaders), and major intelligence successes and failures (which generally consist of efforts to foil internal plots and foreign invasions). We journey to ancient Greece and Rome; China and India, where The Art of War and the Arthashastra first recognized intelligence as providing strategic advantage; the Islamic world; the Middle Ages and Inquisitions; Renaissance Venice; Elizabethan England; French intelligence during the reign of the “Sun King” Louis XIV; the American Revolution and George Washington’s fixation with intelligence; Czarist and revolutionary Russia; and finally, to intelligence in the 20^th century, where most intelligence histories usually begin. Of the book’s 30 chapters, only two are devoted to World War II, and just one to the Cold War. For Andrew, the arc of intelligence history is very long.

If there is a unifying theme to this expansive work, it is that intelligence has almost always been underrated by the political and military leaders who make history and by the writers who chronicle it. For Andrew, intelligence is the Rodney Dangerfield of international politics, never getting the respect it deserves.

In the ancient world, for example, deception played a pivotal role in one of the most consequential naval victories in recorded history, the Battle of Salamis in 480 BCE. According to Herodotus, Persian naval forces vastly outnumbered those of the Greek city-state alliance and were poised to deliver a decisive blow until the Athenian general Themistocles devised an ingenious ruse. He sent a loyal slave to the Persian camp posing as a traitor with valuable intelligence: The Greek alliance was splintering, and if the Persian navy moved quickly into the Strait of Salamis, the Athenian navy would switch sides. The operation was designed to lure the Persian navy into the narrow strait between Salamis and the mainland, where Themistocles believed the Greeks’ smaller and more maneuverable ships could gain the advantage. He was right. Xerxes, the Persian monarch, watched from his golden throne above the Bay of Salamis as the Greeks sank 200 of his ships while losing only 40 of their own. It was a momentous loss at a hinge in history. Had the Persians prevailed, the Greeks likely would have lost the war and the development of world civilization might have been dramatically altered.

Yet the writings of both Herodotus and Thucydides make clear that Themistocles was an exception. Most Greek generals did not regularly use double agents or intelligence of any kind, relying instead on personal seers who claimed to receive divine guidance by interpreting dreams, the behavior of birds, and the entrails of sacrificed animals. Athenian democratic leaders viewed surveillance and deception as beneath them. Most Roman generals (with the notable exception of Julius Caesar, who was the first military leader to code his communications with ciphers during campaigns) also believed there was more utility in divining the will of the gods than the intentions and capabilities of humans.

The Art of War was the first book to argue that intelligence should play a central role in war and peace. It is believed to have been written by Sun Tzu sometime between 544 and 496 BCE, and its ideas are now canonized in military academies and popularized in all sorts of self-help books: Assess yourself and your adversary; subdue the enemy without fighting; use deception to gain advantage; appear weak when strong, incompetent when competent, fearful when brave. Yet here too, Andrew writes, ancient intelligence wisdom was not fully recognized even by China’s first emperor, Qin Shi Huang, who was more influenced by superstition than Sun Tzu’s admonition to gain foreknowledge from people who know the conditions of the enemy.

The Renaissance marked the turning point when Europe became for the first time the intelligence center of gravity. For this development Andrew credits two inventions: the printing press, which spread ideas at unprecedented speed and scale; and the decision of Italian city-states to begin stationing their Ambassadors permanently in each other’s capitals rather than sending them only on specific missions. Since most resident Ambassadors were expected to gather information as well as represent their governments, the recruitment of spies increased, and intelligence came to be seen as more intimately connected to statecraft in Europe.

Venice became the secrecy capital of the world. By tradition, the custodian of official records was illiterate to prevent him from reading the documents he handled. Letterboxes were placed throughout the city for citizens to submit names of those suspected of subversion. Venice’s master codebreaker, Giovanni Soro, was the international celebrity of his day. Masks were so widely used that in 1608 they were banned by statute except during carnivals. With the exception of signals intelligence, which continued to be handled by specialized offices, there was no bureaucratic distinction between diplomacy and espionage in Western or Central Europe for the ensuing four centuries.

Andrew’s discussion of British intelligence history is particularly gripping and detailed. In his view, the reign of Elizabeth I (1558-1603) marks one of England’s most vulnerable and successful periods. Viewed as an illegitimate heretic by the Catholic powers of Europe, the unmarried Protestant queen faced threats of Catholic subversion and assassination at home and invasion from abroad. In response, the queen appointed Sir Francis Walsingham to serve as both her foreign secretary and intelligence chief, the first time that both roles were held by the same person.

Serving from 1573 until his death in 1590, Walsingham built an extensive network of agents across Europe (including most likely the playwright Christopher Marlowe) and oversaw the revival of English codebreaking. Andrew calls the results “the world’s most sophisticated intelligence system” of the day. Although Walsingham’s private papers have not survived, other records show that he enjoyed daily access to the queen and apparently did not shy from speaking truth to power, on one occasion so angering Elizabeth during a disagreement that she took off her shoe and threw it at his head. Walsingham’s most important achievement was decrypting communications that revealed plans by King Philip II of Spain to invade England. Napoleon and Hitler’s invasion plans were also thwarted by British codebreakers. Yet as Andrew notes, historians at Bletchley Park during World War II “had no idea” their codebreaking forbearers had protected the country from similar moments of peril. “No other wartime profession was as ignorant of its own past,” he writes.

Much the same can be said of American intelligence history. Benjamin Franklin is widely regarded as a Founding Father of the United States, but few historians note—as the Central Intelligence Agency did in 1997—that Franklin was also a Founding Father of American intelligence. In Paris, Franklin waged effective covert action propaganda and disinformation campaigns to sway French opinion and secure the crucial French-American alliance during the Revolutionary War. Nor is it widely understood that General George Washington was better at intelligence than fighting. He ran a string of agents and double agents, devoted considerable effort to encrypting and decrypting communications, and devised all sorts of deceptions—including forging fake documents with references to fictitious regiments under his command. Washington’s greatest feat may have been convincing the British that his forces were too strong to attack when in fact they were at their weakest.

Also overlooked is the importance Washington placed on intelligence as President. During his first State of the Union address, Washington requested a secret intelligence fund that within three years had grown to over $1 million, or 12 percent of the Federal budget. Today, by comparison, intelligence comprises less than 2 percent of the budget.

And the “special relationship” between the United States and Britain wasn’t so special on the eve of the World War in 1914. British intelligence went to great lengths to persuade America to join the war effort, including spying on American diplomatic communications, deceiving Assistant Secretary of the Navy Franklin Roosevelt about Britain’s intelligence capabilities and operations, planting stories in American media to whip up anti-German sentiment, and sharing (but hiding the origins of) the now infamous telegram intercepted from German Foreign Minister Arthur Zimmerman offering a German alliance with Mexico that would include assistance to help reclaim Texas, New Mexico, and Arizona territory if war broke out with the United States.

Particularly intriguing for students of history is how one German subversion operation changed the course of the Russian Revolution. In the spring of 1917, the Kaiser approved a plan to transport Lenin from exile in Switzerland back to Russia. Andrew writes that Germany wanted to foment revolutionary chaos, fragment Russian opposition to the Provisional Government, and end the war. Shortly after Lenin arrived in Petrograd, a German representative in Stockholm cabled Berlin: “Lenin’s entry into Russia successful. He is working exactly as we wish.” In reality, however, Lenin’s return set in motion the mother of all blowbacks. While the Mensheviks and Socialist Revolutionaries cooperated with the Provisional Government, under Lenin’s influence the Bolsheviks refused. Instead of fragmenting the revolution, Lenin’s strident position enabled the Bolsheviks to claim that they were the only true revolutionaries as the Provisional Government’s popularity plummeted. “But for German help,” Andrew writes, Lenin “would have remained in exile in Zurich for most of 1917, probably unable to impose his will on his Russian followers.”

Across time and place, Andrew places individuals at the center of the story. The Secret World reads more like a hundred secret worlds, each led by someone who either saw the value of intelligence or didn’t. This approach makes for interesting reading but also some puzzling claims. Among them, Andrew argues that if only Franklin Roosevelt had shown greater interest in U.S. Navy signals intelligence, the U.S. government could have prevented Japan’s surprise attack on Pearl Harbor—even though Roosevelt was an avid consumer of intelligence and a Navy man. Andrew seems unaware that the principal lesson actually learned from Pearl Harbor was the importance of organizational design. Roberta Wohlstetter’s seminal 1962 study, Pearl Harbor: Warning and Decision, finds that signals of Japan’s impending attack existed but got lost in the noise of false alarms and the maze of disjointed intelligence bureaucracies in the War and Navy Departments. Indeed, the Central Intelligence Agency was created precisely to address these coordination weaknesses and “prevent another Pearl Harbor.”

Alas, it has never fully succeeded. Half a century later, my own work and the 9/11 Commission found that organizational deficiencies were once again crucial to understanding why U.S. intelligence agencies failed to prevent a surprise attack.¹ Hobbled by Cold War-era structures, incentive systems, priorities, and cultures, and riddled by coordination problems, the CIA and FBI missed 23 opportunities to penetrate the 9/11 plot. Attributing intelligence failures to individuals may be comforting. But if the goal is learning from past failures to prevent future ones, it is often a counterproductive focus.

The Secret World finds that intelligence has not developed in a linear fashion anywhere. Yet Andrew does not explain any of the patterns he discovers. Why did the great coding capabilities of the Muslim world disappear for 500 years? Why did no American President for 150 years after George Washington utilize intelligence nearly as much as he did? Why did the British allow signals intelligence capabilities to languish for 70 years before World War I?

One possible answer is that the development of intelligence capabilities over time can be understood as a response to shifts in the threat environment. In periods when domestic subversion and foreign invasion threats are great, intelligence tends to be more valued and better developed. When threats recede (or are thought to recede), intelligence capabilities atrophy. Andrew hints that cultural attitudes may also help explain variations in the use of intelligence. The Ottomans, he notes, failed to develop a robust intelligence system when the Venetians did in part because the Sultan thought placing embassies with spies in the capitals of lesser leaders was beneath him. Similarly, he writes that the Russians underestimated the Japanese military in the Russo-Japanese War because of racist views of Japan as a weak and undeveloped civilization. This much is clear: When so many leaders over so many centuries give such little credence to intelligence, chances are that something more systematic is at work.

“Twenty-first century intelligence suffers from long-term historical amnesia,” Andrew observes. Whatever its own shortcomings, The Secret World offers the beginnings of a remedy—though, as might be expected given the very nature of the task, much remains stubbornly hidden.