I just finished a game on tough on a lhuge map. I was arcean and I was stuck between between Korx and Altarians, and they were both waging war on me. Now, even before the war started, i never managed to build a strong enough military. Actually, i've never managed to keep a high military rating, even if i continuously pump out vessels at all time. I usually have 4 factories and a starport on every planet, plus other enhancements, depending on what i need.
So, what should i do to build a strong army?