I subscribe to C-SPAN's "After Words" podcasts. There are some excellent in- depth interviews with authors about the books they have written. At the moment I am listening to Amanda Foreman talking to Eric Foner about her book "A World on Fire: An Epic History of Two Nations Divided". The book looks at British volunteers in the civil war. It can be watched on http://www.c-spanvideo.org/program/Forem
As Foreman says at one point in the discussion - "there are layers upon layers here". It looks at different attitudes within Britain to the two sides of the war. There was much support in England for the confederacy (a fact that wasn't highlighted in the English histories I read as a youngster!). There is also a mirror of the divisions which have affected Ireland.
A fascinating problem - which ever side of the Atlantic you live on!