further, as I recall, we were about the only major industrial power left standing (more or less untouched on the homefront even!) after WWII. There were a whole lotta countries needing rebuilding, and we had a whole lotta just-released-from-the-war-effort industrial capacity. *
The post-WWII boom was the result of a historical oddity from an economic standpoint... something a lot of modern "let's go back to 60's-style income redistribution and expand the Welfare State" neo-coms don't seem to understand. Nor, for that matter, those advocating another global war to boost the economy.
Money for investment in war material comes from somewhere... it's gotta be either taxed or borrowed -- either way, it comes out of the private sector. Which means reduced investment in more productive endeavors. (Really, which gets more return on investment -- a passenger plane or a bomber?)
Now no, I'm not saying that national defense isn't important. Only that looking to massive military spending to bolster the economy is fruitless over the long run.
-K