In few areas of human activity is there such a discrepancy between perception and reality as there is with war. There tends to be a huge difference between what people think war is and what it really is, a thought that returned to me repeatedly as I read a stack of new books.

The gap between expectation and reality drives a bitter new memoir by a former United States Army lieutenant. Erik Edstrom went to war in Afghanistan in 2009 pretty much as a true believer, fresh out of West Point, where, at his graduation, he gratefully shook Dick Cheney’s hand. After a year of what he saw as pointless combat in the southern Afghanistan desert, he came to believe that “America is neither good nor great.” The result is his boiling mad UN-AMERICAN: A Soldier’s Reckoning of Our Longest War (Bloomsbury, 304 pp., $28). It amounts to a kind of “Pilgrim’s Progress” in reverse, an account of how he lost his faith in his country.

“The war on terror strip-mined my soul,” Edstrom writes. “It strained my relationships, destroyed my notion of patriotism, eroded my support for American foreign policy, dissolved whatever faith I may have once had in religion or God, and made me deeply sad.” There have been several excellent memoirs by veterans of our current wars, but this is the first one that reminded me of the disillusioned writings of British veterans after World War I, grounded in a deep new distrust of the nation that sent them to war and in the officers who led them in combat.

I don’t agree with much of what Edstrom writes. For example, I think the United States was right to invade Afghanistan after 9/11 (yet wrong to stay any longer than six months). But even as I differed with his words, I was glad to read them. Edstrom is asking hard questions that both the American people and their leaders have sidestepped for years. For example, he calculates that the United States military has killed more than 240,000 civilians in its recent wars, some 80 times more than the number of Americans who died in 9/11. How much is enough? Like him, I feel that over the last two decades our country has drifted from its ideals — for example, by torturing foreign prisoners, by militarizing many of our civilian police forces and by tolerating extreme income inequality, and then by electing a president who embraces all of those things.

The discrepancy between American memory and reality is one of the themes of CAPTIVES OF LIBERTY: Prisoners of War and the Politics of Vengeance in the American Revolution (University of Pennsylvania, 336 pp., $39.95). The horrible conditions in which American soldiers were held as prisoners of the British are widely known. About half of them died in captivity, many thousands of them aboard prison ships anchored in Brooklyn’s Wallabout Bay, later home of that borough’s Navy Yard.

Less remembered is the cruelty with which Americans handled their British prisoners. That is the main topic of this study by T. Cole Jones, a historian at Purdue University. American leaders, most notably George Washington, tried to follow the rules of war. But state governments and their militias had the responsibility for housing and feeding enemy prisoners, and they had neither the money nor the inclination to treat them well. The result was that British P.O.W.s were shuttled from camp to camp, sometimes marching in winter without shoes or adequate food, while being prodded along by the bayonets of disgruntled American militiamen. Jones notes that the mortality rate for British captives was higher than that of Union prisoners during the Civil War at the notorious Confederate prison camp at Andersonville, Ga.

Retaliation for the poor treatment of Americans by the British was part of the justification for this harsh approach. But the core reason, Jones argues, was that as the war ground on, it became increasingly vicious, with aspects of civil war. After the battle of Kings Mountain, S.C., in October 1780, he notes, Revolutionary soldiers shot down Loyalist militiamen offering to surrender, and later hanged some of their leaders. Such cruelty became the norm for both sides, he adds.

The participation of women in war also tends to be excluded by the public imagination, a failing that two new books seek to address.

Simon Parkin’s A GAME OF BIRDS AND WOLVES: The Ingenious Young Women Whose Secret Board Game Helped Win World War II (Little, Brown, 320 pp., $29) depicts part of the battle between Allied shipping and German submarines during World War II. Parkin, a contributing writer at The New Yorker, brings to life one of the most elusive aspects of war, showing how a military can develop an understanding of what the enemy is doing and then, without adding any additional firepower, find ways to stymie those actions.

Early in the war, German U-boats sank so many freighters crossing the North Atlantic that Winston Churchill and others began to fear the war could be lost for lack of supplies. In response, the Royal Navy in January 1942 formed a secret unit, staffed mainly by young women, that eventually overhauled British anti-submarine tactics. This unit, called the Western Approaches Tactical Unit, was tucked away on the top floor of Derby House, a building in downtown Liverpool. There it studied reports from sea on German submarine movements both preceding and following successful attacks. It then replayed those attacks, using a giant board game the size of a room, with an eye toward devising new ways of countering them. In its work it went from each British warship operating on its own to learning how to coordinate counterattacks with others. The unit even developed plays, akin to those a football team might use, and gave them shadowy code names like “Half-Raspberry,” “Observant” and “Artichoke.”

A skeptical admiral, one of Britain’s most highly decorated submarine commanders, arrived one day to role-play in the game as a U-boat commander. He was “sunk” in five successive games. At first he thought his opponents were cheating. Finally he was persuaded that the game wasn’t rigged, and that he indeed had been trounced by a 20-year-old woman who had never been to sea or even seen a submarine. Eventually some 5,000 Royal Navy officers went through training at the unit, learning the plays and how to reinforce one another in going after U-boats. By mid-1943, British anti-submarine operations had become so effective that the “Battle of the Atlantic” was basically over, clearing the way for the tidal wave of American troops and supplies necessary to carry out the D-Day landings a year later.

The book would have been more illuminating had Parkin addressed comparative questions, such as why the Royal Air Force was so much better early in the war at giving strategic direction to its combat operations than was the Royal Navy. I suspect one reason was that the air arm, founded just a few decades earlier, was less fettered by tradition than was the sea service. But Parkin does not pretend to be presenting an academic study, and the story is compelling as it is.

In an error typical of accounts of World War II resistance movements, A HOUSE IN THE MOUNTAINS: The Women Who Liberated Italy From Fascism (Harper/HarperCollins, 416 pp., $29.99) is burdened by a subtitle that overstates the case. The Italian Resistance did not free Italy from the Fascists or the Nazis; the Allied armies did. And they did so slowly, because, as the author, Caroline Moorehead, recognizes, Italy was a sideshow in the war. The Allies’ road to Berlin simply did not go through Italy. Also, the British and Americans were deeply suspicious of Italy, which after all had been on the wrong side for most of the war.

As other books on the resistance movements have told us, most of what the partisans did was simply to survive — a great achievement by itself because it showed there was a living alternative to Fascism and Nazism. As in other countries, “the songs they composed were all about hunger, ice, fear.”

Moorehead, the author of several other works on World War II resistance, is more persuasive when she looks at how these women were not recognized then or now for the roles they played, often as messengers, sometimes as organizers and fighters. For example, the Italian Communist Party excluded female partisans from its postwar victory parade. Women with other organizations who were allowed to march were jeered by onlookers as prostitutes. And when one talented female resister became vice mayor of Turin, her proposals for vigorous postwar reconstruction were dismissed by other city officials, with one saying: “Ah! Ah! pretty, bizarre little head.”

Ask the average well-educated person about the Napoleonic wars and you’ll hear about Waterloo, and perhaps some other battles like Ulm and Austerlitz. But here again there is a huge gap between what we remember and what actually happened. Alexander Mikaberidze, a historian at Louisiana State University at Shreveport, argues persuasively in THE NAPOLEONIC WARS: A Global History (Oxford University, 960 pp., $39.95) that the deepest and longest-lasting effects of the 23 years of fighting actually occurred outside Europe. Some examples: The threat presented by Napoleon forced Britain to go easier on China than it would later in the 19th century. Napoleon’s invasion of Spain in 1808 cut off that country’s monarchy from its colonies in South America and so began the series of events that led to independence for almost the entire continent of South America. And his desire to make life more difficult for the British led to his willingness to sell a large part of North America to the young United States. The Louisiana Purchase in turn sparked rapid American expansion westward, fueled in part by the economic boom that came from shipping American grain and flour across the Atlantic to feed British and French armies. But as Mikaberidze notes, Napoleon’s decision to sell the territory would prove disastrous for the First Peoples tribes west of the Mississippi.

If you’ve never read a book about Napoleon, this is probably not the place to start, unless you have a great deal of patience. And if you do know the basics of the era, you might want to skip the first 332 pages, which at times feel like the literary equivalent of Napoleon’s wintry retreat from Moscow. Mikaberidze dwells overmuch on tactical battlefield matters and on ephemeral micropolitical obscurities like the Septinsular Republic, the Parthenopean Republic and the principality of Piombino.

In history, as elsewhere, just because a subject is important doesn’t mean that a book about it is interesting. An example of this is ALL HELL BREAKING LOOSE: The Pentagon’s Perspective on Climate Change (Metropolitan/Holt, 304 pp., $30). It is, quite simply, one of the dullest books I have ever read. Essentially it summarizes about 15 years of reports and congressional testimony by Pentagon officials. On top of that, the writing of Michael Klare, a professor from Hampshire College, is pedestrian. One sample: “As global warming advances, one climate shock after another will ricochet across the planet, leaving chaos and misery in their wake.”

One of the oldest books about war remains one of the most illuminating. Michael Nylan, an expert on early Chinese history at the University of California at Berkeley, reminds us of this with her new translation of Sun Tzu’s ART OF WAR (Norton, 160 pp., $24.95). I am not capable of judging the quality of her translation, but I can report that the clarity of her English prose is commendable. And there is so much wisdom in this little volume that we should take advantage of any opportunity to revisit it.

“Best is to subdue the enemy’s troops without ever engaging them on the battlefield,” is how Nylan translates one of the ancient Chinese author’s most famous sayings. She translates another: “To be prepared everywhere is to be strong nowhere.”

Some of these passages have the quality of poetry:

Do not take the enemy’s bait.

Do not stop an army on its way home.

When surrounding the enemy, leave him a way out.

One passage brought home to me the fundamental differences that remain between the Western and Chinese ways of war. I don’t think most American generals would endorse the advice that “only the most perceptive ruler understands how to employ spies, and only the most humane and just commander knows how to put them in the field.” Certainly this is at odds with President Trump’s stated views of how to handle prisoners of war.

Sun Tzu, who lived about five centuries before Christ, would have understood the principles of “stealthy” detecting-evading aircraft. Basically, it is a warplane designed to deny information to the foe by reducing its radar and heat signatures. In other words, it is made expressly to create a discrepancy between appearance and reality.

Peter Westwick’s STEALTH: The Secret Contest to Invent Invisible Aircraft (Oxford University, 272 pp., $27.95) is a readable and valuable contribution to Cold War history. Westwick, a historian at the University of Southern California, argues that it was no accident that the two companies charged with developing the first stealthy aircraft — Lockheed’s F-117 (which despite its “F” for fighter designation was a light bomber) and Northrop’s B-2 heavy bomber — were both located in the Los Angeles area, which Westwick describes as having a looser, more creative culture than much of the rest of the country. One striking cultural connection: The engineer whose name is listed first on the F-117 patent was Richard Scherrer, who in the 1950s had moonlighted to design some of the rides at Disneyland, including Flying Saucers and Dumbo the Flying Elephant. Designers of the curvy B-2, essentially a flying wing, eventually developed the ability to “look at a surface and understand how a radar wave would interact with it” by “riding them in their imaginations, surfing them as the waves bounced off the aircraft.” Westwick notes that it was Southern California aerospace engineers who streamlined the surfboard and invented the windsurfer and the boogie board.

Reading about the invention of stealthy aircraft made me think more about conflict and perception. The greatest trick of war is that, like a virus, it manages to stay one step ahead of humans. There seems to be no end to its ability to fool people into believing that violence is the answer to our problems.