At the risk of being crass, we've said on several occasions that the Paris attacks, the San Bernardino massacre, and the wave of sexual assaults that have swept Western Europe are the best things that ever happened to Donald Trump's presidential campaign. It seems exceedingly likely that Trump had very little conception of what was going on in the Balkans when he stormed onto the political scene last summer with inflammatory comments about Mexican immigrants. As luck would have it, just two months later, Europe's migrant crisis reached a critical tipping point when Hungarian PM Viktor Orban built a 100-mile...