1. How do you defeat a pack of 5 units of King Tigers?


Anyway, I tried tactical bombers, the biggest AT guns I could get, heavy infantry ambushes, tank destroyers and tanks. All my artillery was just a joke. The AI kept the KTs together with lots of support and while I eventually picked off all of the supporting units, the KTs were still pretty much invincible. If there are two (or three or more!) together it seems like attacking with anything at all is just a suicide charge. Since I won the scenario I'm not complaining that the KT is overpowered, but I'm wondering what the "correct" method to handling these scary beasts is. The only thing that "worked" was delaying them with infantry in heavy forests and cities.
2. AT guns. What good are these? I bought the best I could and put them in all sorts of places. Forests. Hills. Plains. Cities. I understand how initiative works and how terrain caps initiative, but on offense or defense I struggled to get my money's worth on AT guns. Is the German armor on this scenario nightmarish, or am I doing something wrong? I don't think I could have defeated a human player with AT gun ambushes. Most of my AT guns bounced shot after shot against German armor and died very quickly. Oddly enough they only had any mentionable successes against German tank destroyers and scouts, but infantry would have been better and cheaper in all of those situations.
Towards the end of the scenario I could have swore I noticed an AT gun or two fire in support of my adjacent infantry units, but I don't see anything in the manual about this and I don't remember anything in the tutorial either. Am I just imagining things or are AT guns really meant to support units on defense like artillery can? I'm struggling to come up with a reason to want AT guns when I could buy mechanized infantry or armor instead.