Story highlights Britain voting to leave EU is the worst step backward for Europe since the end of World War II, writes Charles Kaiser

Progressive voters must recognize similarities between the Brexit appeals to racism and Trump's attacks on Muslims and Mexicans, Kaiser says

Charles Kaiser is the author of "1968 In America," "The Gay Metropolis" and, most recently, "The Cost of Courage." The opinions expressed in this commentary are his.

(CNN) The numbing news that Britain has voted to leave the European Union is the worst step backward for Europe -- and for Western civilization -- since the end of World War II.

There were tens of millions of military and civilian casualties in Europe from that hideous conflict, and it left much of the continent in ruins. But in Europe, World War II also had two extremely positive effects. First, unlike the United States, where there were relatively few casualties at home, the personal experience of the horrors of war by millions of European civilians inoculated their countries against all-out war for the next seven decades.

Charles Kaiser

And, second, within a remarkable group of forward-looking men and women, the end of the war spurred one of the greatest impulses toward unity of all time. These were the visionary politicians like André Boulloche, a hero of the French Resistance, who pushed for the creation of what would eventually become the European Union.

Boulloche paid for his heroism as a Resistance fighter with a year inside three German concentration camps, and the loss of half of his family after they were arrested by the Gestapo, a saga I recount in my recent book "The Cost of Courage." But like so many other extraordinary European survivors of World War II, Boulloche managed to transform his terrible suffering into a force for good. He became a Socialist politician, the mayor of a small French city near the border with Germany, and a member of the National Assembly.

In a supreme act of intellectual jiu-jitsu, Boulloche took all of the ghastly energy from his wartime incarceration and turned it around to fuel a lifelong devotion to reconciliation between France and Germany. As Socialist leader and future French President François Mitterrand declared at Boulloche's funeral, "When he turned toward the Germans, he was the first among us who knew how to say, 'My friends.'"

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