Yes it was the force of the fire however a waterbender or airbender cannot break through a wall like that with the force they can produce. As you pointed out earlier the general raised a slab of wall to protect himself from Aangs airbending move. Now why didn't that break the generals wall? It looked just as powerful as an attack Aang could ever produce.
What im trying to focus on when a firebender fights a waterbender, it's the fact that a firebender has more martial arts experience than a waterbender, waterbenders arent acustomed to learning it. This gives them an edge, i can't say that firebending is??the best element(i like it the most though),??they all have eqaul advantage but because the firebenders??have the martial arts, they dont have to depend on their bending alone this gives them an advantage. For a Firebender to use lightning, they need to momentarily knock their opponet out with thier martial arts to give them enough time to separate the energies and direct lightning. Of course a prepared waterbender could easily defend from lightning. If the General lowered Katara into the earth so easily, why cant all the other earthbenders do that to the fire nation soldiers? this war should be practically over.
Now about the easter and western world thing... what you say is true about the real world but not in Avatar world. The Fire nation created all the ships and things on their own, there is nothing saying the earth kingdom invented all these things first and the fire nation made them better, all the earth kingdom can claim is the hot air balloon.
And finally i have not been making asumptions, i have been using evidence from the series to back up what i say. Im not trying to??offend you or anything i just enjoy a good arguement every now and then. I hope we can discuss this further.
