The nice thing about SWN, is that you can make it as big as you want. A Battlecruiser is bigger than most ships in the Post-Scream era, so just make it as big as you need. Of course in the intervening time, the numbers would naturally have been exagerated (or shrunk if you wanted the troopers to appear more heroic).
So, say there were 1,000 troops.
The enemies and conquered territories might say that there were actually 10,000 troops so it appears that the invading force was so overwhelming they had no choice but to surrender.
The troopers themselves tell the story that they conquered everything in site with only 100 troopers. See how brave we were?
History is full of things like that were after just a few decades it might be almost impossible to get the real numbers...
This isn't Traveller, so the Bruxelle holds as many Troopers as you need for the story...
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