as being a deterrent, although the necessity to register will always put some people off.
One of the problems with forums nowadays is that almost every site has one, and people can tend to react with apathy: "Here we go again, another forum populated by a few wierdos who ramble on about conspiracy theories all day long".
Stick at it and I'm sure you'll build a nice little forum, but it will take time. The one piece of advice I would stress above all others is to control the forum firmly. If you don't do that it will rapdily degenerate into a foul-mouthed slanging match. Note that I said 'will' and not 'might' - there's no doubt about it. Keep it clean, even though you'll be accused of being a prude, being a sad person, and a spoil-sport, and you'll end up with a thriving little community of people who know they'll get some interesting and intelligent content.
Don't allow joke threads - no two people have exactly the same taste in humour - and don't allow religious/racist intolerance of any description, it's the kiss of death and anyway it's illegal. Avoid the 'England for the English' element who go looking for receptive forums - they'll cause untold problems, and most of them don't have a single intelligent thought in their heads anyway.
A good forum, if it's busy will take up a great deal of your time. People will expect to see you in there every day, and if you're not they'll get the feeling it's drifting.
Good luck with it - I think you have the makings of something very interesting, given the theme of your site, and I'll certainly pay you a visit from time to time.