I've noticed a chain defense strategy that involves switching the monarch to the chain target, as a new target is made apparent switch monarchs again.
While this requires an impressive amount of coordination I feel like it's an abuse of game mechanics, pulling this off multiple times in war doesn't seem to make sense in the context of the game.
I believe the monarch bonuses, specifically the 10% defense in war, should slide over time in to full effect just like other effects of war.