Back in the 1990s something happened in central Bosnia-Herzegovina that inspired people to this day and helps explain why that country now has more men fighting in Syria and Iraq (over 300), as a proportion of its population, than most in Europe. The formation of a "Mujahideen Battalion" in 1992, composed mainly of Arab volunteers in central Bosnia, was a landmark. Today the dynamic of jihad has been reversed and it is Bosnians who are travelling to Arab lands. "There is a war between the West and Islam," says Aimen Dean, who, as a young Saudi Arabian volunteer, travelled to...