A little Internet research showed me that there have been three British Afghan wars (1839, 1878 and 1919) - and Britain won them all.
We never took the country over but withdrew each time having inflicted military defeat on them and having achieved our objectives.
So what's all this talk of defeat about then?
More trendy anti British re-writing of history perhaps?
PS - I don't think we should be there now though - but that's another matter.