[Puke]

holding ground should not always be your goal. the Russian army (until the end of WWII) held the doctrine that anywhere they marched became Russian soil. Thus, they fought to the man and bullet defending their positions. This wasnt always a good thing.

If you are fighting to destroy an enemy, and cripple their ability to make war - rather than to gain territory and bolster your industrial base - then you may not need to wory about holding ground. The defender must hold ground, but you can raid systems, destroy colonies, then pull out. sometimes you cant afford to hold worlds, but you can afford to continue an offensive untill you can recolonize them later.

Other times, holding teritory is crucial, because you need their production, or their resupply depots, or need them to slow down a counter attack.