Most of what is said above is true, however maybe instead of lowering time it takes and resources so much, why not just lower time?
I mean, from however many days it took before to what you're proposing, that's a huge difference in itself, let alone also lowering the resources for it, in fact it makes more sense to keep the resources the same or increase it to stop simmers and turtles.
However, if you wanted to help increase aggressive players, perhaps you could put a restriction on the amount of times you can use it?
Say, you can use it twice, or 3x the amount of times for each victory procession you have had in your city? I don't know, just an idea.