Historically, yes they have been. The WWs provoked big jumps in purchasing, plus enabled a societal change for women to gain employment if they chose. Of course, WWI didn't have such a great effect on Germany (I think inflation went way way up... needed a wheelbarrow full of $$$ to buy bread or something), but they started it, so I suppose thats "karma" or what have you.
This new 'war'... I don't know... It's really not a war, it's more of a prolonged international military presence, and I have to tell you, it really hasn't been good for the economy. Or at least the economy hasn't been doing so well since it's started. The last I saw of the US national debt it was something like 10 trillion. TRILLION!! Because it's several million dollars per missile and several billion dollars per jet to shoot them. The jobs created are outweighed by the sheer cost of these items. Additionally, it's an unpopular war, which means people would not be particularly willing to financially support it (buying war bonds, etc.)
So, historically, yes wars have improved economy (post-war boom), but it feels almost as though the current administration relied on that phenomenon to get them through this thing, which it simply hasn't.
