Western European countries needed extra workers during the great economic boom that took off after the Second World War. They imported these workers from the old empires and other developing areas. Then the European Union allowed a considerable mobility of the immigrants after they arrived. Generally, these countries didn’t give any thought to the assimilation of the immigrant “guest workers.” Either it was assumed that they would go home after working in Europe or the possibility of problems didn’t occur to any government official. So, all countries now have a problem with the descendants of the immigrants who never went home and—often—did not assimilate.
Belgium brought in lots of Turks and Moroccans. Today there are about 640,000 Muslims living in Belgium, where they make up about 5 percent of the population. Belgium turned out to be a particularly difficult country for assimilation. It is, in a sense, a “made-up” country created for the convenience of other countries back in the 19th Century. It is divided between French-speaking Walloons and Dutch-speaking Flemings. Efforts to pacify the factions produced competing and overlapping government bureaucracies. Quarrels between the two groups continue, so no one gave much thought to the immigrants and the immigrants had no clear national identity to try to join.
Then the oil shocks of the 1970s heralded a period of economic troubles that included the dying of the coal and steel industries in which the immigrants and many native Belgians labored. The immigrants and their descendants adapted less well to the changes than did the native Belgians. Poverty and isolation compounded each other. Now Belgium has a large population of citizens who are considerably angrier with their country than are the supporters of Donald Trump. Many of them turned to petty crime and drugs. In these miserable conditions, street preachers arose and won followers by preaching that their victimization arose from their faith. An uncertain share of them has embraced radical Islam. Even when not violent activists themselves, many Belgian Muslims are so estranged from Belgian society that they are willing to turn a blind eye to the violent among them.
Then came the Islamic State. Some 560 Belgian Muslims are believed to have gone to fight for the Caliphate. Belgian cops were glad to see them go. Belgium’s counter-terrorism forces are under-staffed and overwhelmed. Maybe the Islamists would get killed. Many did die in all likelihood. Now, some 120 of the veterans have returned. They have been at the heart of the recent spectacular terrorism: the guns for the January 2015 “Charlie Hebdo” attack came from Belgium; the November 2015 Paris attack was planned in Belgium; and the March 2016 attack in Brussels was carried out by Belgian-born Islamists.
Now Belgium is trying to make up a lot of lost ground in both security and assimilation.
NB: The title to this piece is the punch-line to a French “Belgian joke,” equivalent to the one-time Polish or Blonde jokes in the United States.
 In Germany it’s called the “wirtschaftwunder” (the Economic Miracle); in France it’s called “Les trente glorieuse” (the Glorious Thirty [Years].”
 The Congress of Vienna (1814-1815) redrew the map of Europe after the Napoleonic Wars. To guard against a resurgence of French imperialism, the Congress tried to strengthen the countries on France’s northeastern and southeastern borders. In one case this meant adding the Catholic former Austrian Netherlands (today Belgium) to the Protestant Kingdom of Holland. The Catholics rebelled against Protestant rule in 1830. Rather than resist this by force or partition the territory between France and Holland, the Great Powers accepted independence. Ooops.
 “Belgium’s jihadi problem,” The Week, 8 April 2016, p. 11.