The guilty verdict in the trial of the former marine who murdered Chris Kyle, the heroic “American Sniper,” may provide a measure of closure to the moral melodrama surrounding the American military role in Iraq. Kyle, the Navy SEAL marksman who believed that fighting a war meant winning it, challenged the anti-war narrative, which in recent years has consigned the United States to the nether realms of immorality. In his life and death, he came to personify American heroism and villainy.

Since the end of World War II – especially in Viet Nam and Iraq – American military power has been morally suspect and increasingly vilified. The toll of American soldiers who fought and died – in vain, anti-war critics alleged – peaked at 58,000 in Viet Nam. For the current generation, the war in Iraq has been its cherished immoral war, resulting in 4,500 military deaths (only 1,500 more than the number of American civilian fatalities on 9/11).

I never served in the military. I was too young for Korea, too old for Viet Nam, and too committed to the study of history to relinquish my educational deferment from the draft. I remained a perpetual observer, my perspective indelibly molded by the last “good” war waged by the United States: World War II.

The December after I turned five, my father was engaged in our annual ritual of setting up my beloved Lionel electric train for the weeks of pleasure that it provided. It enabled me briefly to control the adult world of our living room, steering a locomotive around curves of tables and through tunnels of chairs, sounding its whistle along the way. That December, my father was repeatedly interrupted, rushing into the kitchen to listen to our only radio broadcast its stunning news. It was December 7, 1941.

Forest Hills in Queens was distant from war zones in Asia and Europe. But I can still hear the nighttime air-raid siren drills and remember our grade-school retreats into to the halls for “protection.” Planting a Victory garden in the playground, and selling war bonds in a school competition (which I won because my father partnered with me and sold bonds on my behalf to his fellow patriotic colleagues), I was delighted to participate in the war effort.

Aside from the First-Aid kit that my uncle, a pharmacist, prepared for me in the event of a war-time emergency, my greatest thrill came in Teanack, New Jersey, where I met my hitherto unknown cousin Billy. He arrived in his United States Marine uniform, bedecked with ribbons that I admired and coveted. He was clearly enjoying a brief furlough before his next mission. A few months later that turned out to be the Battle of Tarawa, which erupted in 1943 on the Pacific atoll where he was killed along with 2,700 other GIs.

Measured by casualties, Tarawa was a “minor” island battle. At Iwo Jima 6,800 Americans perished; at Guadelcanal, 7,100; at Okinowa, 14,000. During World War II nearly 300,000 Americans fell in combat. Then there were the Six Million. I learned about them from the Life Magazine issue dated May 7, 1945, my ninth birthday.

For the little boy I was, World War II defined the horrors of war, the obligation to defeat the enemy, and the meaning of patriotic loyalty. Those experiences made me as an adult a patriotic outlier. From living in Israel for two years, I learned new lessons about the necessity of just wars that reaffirmed my boyhood inclinations.

Talk show host Bill Maher may call Chris Kyle a “psychopath patriot.” Michael Moore labeled (libeled?) snipers “cowards.” To an MS-NBC reporter, Kyle was a “racist” who went on “killing sprees.” “American Sniper” reminded Canadian comic Seth Rogan of Nazi propaganda. Others of lesser notoriety in the press identified Kyle as “a hate-filled killer” and an “American Psycho.”

So be it. Chris Kyle’s autobiography “American Sniper” and the film based on it do not tell a pretty story. Neither does war. But heroes deserve honor. I learned that long ago from my cousin Billy.

Mr. Auerbach, professor of history emeritus at Wellesley, is the author most recenty of “Jewish State, Pariah Nation.”