[Tuor in Gondolin]

Originally posted by Pitchwife
Last not least, I'm not convinced that most of the Dwarves' fighting was being done underground. Unless they were really busy fighting nameless things gnawing at the roots of the world all the time, I'd rather think that any battle that had them facing the enemy within their own subterranean homes was already half lost. Wouldn't they do their damnedest to repel any enemy way before they came close to their gates?

I believe there were numerous dwarf/orc battles fought
underground.

LOTR, Appendix A

Thrain...stood up and said: 'This cannot be borne!'
That was the beginning of the War of the Dwarves and the
Orcs, which was long and deadly, and fought for the most
part in deep places beneath the earth.
...When all was ready they assailed and sacked one by one
all the strongholds of the Orcs that they could find from Gundabad
to the Gladden. Both sides were pitiless, and there was death
and cruel deeds by dark and by light. But the Dwarves had the
victory through their strength and their matchless weapons,
and the fire of their anger, as they hunted for Azog in every
den under mountain.