I freely admit that I'm not entirely up on my fluff, but where do you get that there are only a thousand chapters? I had always assumed that there must be far, far more, as to try to go to war with such a tiny force on a galactic scale is insanity. Allow me to explain.
1000 chapters * 1000 men each = 1,000,000 space marines total.
There are about two hundred billion stars in the milky way galaxy. Clearly all those don't have planets, and many of those planets won't support life, but if one in two hundred thousand suns has a planet worth colonising, that means that there is exactly one space marine per useful planet in the galaxy.
Take another measure. The earth has about six billion people. If every single space marine in the galaxy were to invade earth, we'd only outnumber them by six thousand to one. Even given that the majority of those would be civilians, and that their technology would be far superior to ours, those are still unbelieveable odds.
Take a third measure. In World War II, the United States (not counting any of the other allies or axis) had five million men under arms; i.e. serving the military in some capasity.
Even if the average population per planet is lower in the year 40,000, and even if there are fewer interesting planets than I predict, and even if the people who they're fighting have far inferior technology (we all know that's not true, but for the sake of argument I'll include it) and even if we include the Imperial Guard as a supporting force, a million men is not a viable fighting force in a galactic wide conflict. It's not even all that big in terms of conflicts on earth.
Though this is still an interesting project. I'm still looking for a name for my own forces. Maybe I'll find one here.
