This would require a modification to international treaties regarding chemical weapons, but here goes.
Take a nicely potent aneasthetic that will hang around near the enemes area. Then, blanket that area with the substance, putting all your enemies to sleep, so that you can go in and take them prisoner while they're still drunk.
Alternatively, give them highly addictive drugs. They'll be too busy searching for drugs to notice that you've invaded.-- Selky, Sep 28 2009 pssst <takes [Selky] aside>I'm pretty sure this has been done literally to death...treaties or not.-- 2 fries shy of a happy meal, Sep 28 2009 It's been tried. Lots of people died ....
If you knock someone out, they can end up in a position where they choke to death.-- 8th of 7, Sep 28 2009 'WIBNI?' - no, it WBNI-- loonquawl, Sep 29 2009 I think the Russians used this method when a theatre was taken over by Chechen rebels - they piped gas into the theatre and when everyone was dropping off, they stormed the place. There were, I think, quite a few deaths.-- zen_tom, Sep 29 2009 random, halfbakery