The episode begins by Earth Force commandeering the base to use it as a staging point for an invasion of a planet that is involved in a civil war. It seems VERY odd to Sheridan and his crew that the Earth could become involved in this matter, as it doesn't to involve anyone but the inhabitants of the planet AND because using B-5 that way violates the purpose for its creation! But, considering they are ordered to billet the 25000 soldiers, they don't have much choice.
The main concurrent theme is relationships. First, coincidentally, the General in charge of the invasion is the Doctor's father. This brings up some interesting points concerning their relationship and how tough it is to grow up in a military home. Secondly, the way the military relate to the crew of B-5 is interesting--and often VERY tense.
The ending of the episode is very sobering and points to the utter futility of it all. A bit preachy? YES. But still pretty stirring and worth seeing.