Dwarves, like all societies, go to war. So naturally, they must have some sort of normal war tactic. Hollywood loves the image of the mass charge, every man for himself, try to kill off more of the foe than your buddies. This might work for the "barbarian" humans, but to me, the dwarves, being a serious, dour race, would take war a bit more "seriously." To me, the dwarves would take up a style of fighting like the Roman legion. That is, neat, orderly, timed switches for when the front rank gets tired and needs to go to the back for a break (a soldier has only enough energy to fight for about 15 minutes), holding each other's backs to provide support and to drag them back when they die or are injured, and so on. In short, I see them as using a Roman-legionish type of warfare. But these dwarves wouldn't take the exact, word for word, roman legion. No, these people are anatomically different from humans. To be frank, their shortness would lend them admirably for gurilla warfare, but there honor won't let them simoy fight long range. No, they use axes.
Again, I look at history. Which society liked using axes? Egypt. What are axes good for doing? In short, what is their advantage over other weapons? A swing from an axe will take out an enemy, and go through armor like a ballista bolt through a sheet of paper. But the main disadvantage of the axe is that you only get one swing- of you miss, your axe blade is somewhere near the ground, and your agile opponent has a blade at your throat. In fact, to take advantage of the axe's benefits and the versatility of the sword, the falchion was born, which was heavy like the axe to punch through steel.
So in summary of all this, here is how I see the dwarves waging war, based on the facts I have presented above, and what I feel dwarven virtues are.
The dwarves use their shortness for ambush. Hiding on with side of the road (perhaps covered in stones if given time to prepare in hilly terrain?), they wait till the enemy is between their forces. A signal will be sounded- perhaps a bugle, or drums, or a whistle, given by the commander. The dwarves, in triplets, will attack the flanks of the opponent. The first dwarf will swing the axe, if they miss, they second attacks. The triplet will fall back, and then dart in, and the second dwarf will sing first, and so on. Such an attack will take advantage of ther height, while still following their honor. It will also make up somewhat for the disadvantages of their chosen weapon: the axe. The technique could also apply to hammers, which is another weapon associated with the dwarves.
I would also be interested in hearing other ideas (and perhaps a little of th logic behind then) in this topic, as I would be interested in hearing critiques in this particular idea.