This stratagem is available either to any invaders, or to defenders with fortified baggage.
Can you put Bge (I) inside a fortified BUA in order to use the stratagem?
The reason I ask is that armies with no access to fortifications for their baggage have to place their baggage inside a fortified BUA if they want it protected. But while only Bge (O) can gain a combat benefit from defending fortifications, the words in the section about the Delay Battle stratagem don't say anything about being behind fortifications you can benefit from, merely about being inside fortifications.
Also, there are a number of armies which don't have the option of Bge (O), so the stricter reading of the rules suggests they wouldn't be able to even try to use the Delay Battle stratagem if defending, and that seems a little unfair.
