The main thing I have read about the fighting in the Huertgen Forest is this.
GIs were always trained to "hit the ground" when they heard incoming artillery fire. In dense forests like the Huertgen,that was exactly the wrong thing to do. The Germans fired at the tree tops which sprayed shrapnel like hail. Stretched out on the ground, one only made a larger target. The correct thing to do was to hug a large tree.
A friend of mine who fought with the 28th in the Huertgen ended up in a POW camp. He survived the war.