Also Kai attacking along the whole front would decrease the the chances of being encircled by the enemy. But then again this war is always going to be desputed.

Also when a border is only 40 miles away it might take a foreing nation 2 hours to advance if it is 400 miles it could take months if not more. You are correct in regards to artillery however it takes an army to capture the city not just bombs or shells as it was proven in the brutal 900 day siege when the Germans wanted to shell the city into submission.

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The war against Russia will be such that it cannot be conducted in a knightly fashion. This struggle is one of ideologies and racial differences and will have to be conducted with unprecedented, unmerciful and unrelenting harshness. -Adolf Hitler