This takes the fun, mystery and 'tacticalness' (I know its not a word but I like it, BACK OFF) out of the game.
I feel it enhances the game to the veterans who have friends all over that can share this information inter provincially and puts anyone who is causal/quiet at a HUGE disadvantage. Essentially it will turn the game into an eye for eye scenario every single time you attack.
It also puts certain races who can rebuild fast and hopefully defend a retal (Ex. Gnomes) at a disadvantage because they have no time to get any type of defense built back up due to everyone knowing who hit who.
I liked the idea of going to bed, getting smashed and having like 3 prov mates spamming asking "who hit!?!!??" with their attack page filled with troops and their fingers twitching on the attack button but a blank target.
Keep communication going and helps avoid large alliances smashing everyone.