Most of it was taught to other countries by the British!
You are right, there have always been terrorists, many of whom now form legitimate governments. The IRA blew up the household cavalry and Lord Mountbatten, it is nothing new, one reason security was everywhere yesterday!
The royals are different, but only up to a point and that doesn't mean their children are more important than anyone elses. If it's OK for any other British soldier to be fighting in Iraq or Afghanistan, then Harry and William should, as paid members of the armed services, also go!
If they are not going to be 'real' soldiers, they should resign their commissions. All other soldiers, clerks, musicians, etc are sent out to fight, so the people who organise or have other trades are not exempt. If it is purely for the 'experience' for if he becomes King, then do it unpaid!