Less than half of the migrants who have arrived in Europe during the past two years are from Syria. Most are from other overpopulated countries in Africa and Asia from Morocco to Bangladesh. Many destroyed their national identification documents to avoid deportation.  As for the mass exodus of military aged males from Syria, they are leaving the mess to the women and children back home.  Fortunately enough military aged males remained in occupied Europe to defeat Hitler  in WW2. But no one offered them an open-door invitation, either.