As long-standing rivals, the relationship between the Empire and the "Freedom Legion" may not be as all-encompassing in its explanation of "love-hate" as between Albion and Old Charlemagne, but they are thoroughly familiar with each other, which is basically a given. Hence, it was not surprising for the Empire to predict the trump card of the "Freedom Legion"; considering the technological level of the Republic, strategic and tactical needs, the previous combat records of the commander of this operation, combined with the objective environment, it is not difficult to deduce the Republic's only viable option.
"Strategic Attack Spells would affect ordinary civilians, and a full-scale attack would be not only ineffective but also play right into the hands of the Empire. The only ace you have under your technological conditions is the electromagnetic pulse attack."