Deep orcs may be generated peaceful towards orcish player characters.
Deep orcs are primarily found within the Ruins of Moria, where groups of deep orcs are generated both on level creation and by random generation. Random monster creation in the branch is heavily biased towards orcs - 7⁄10 of the orcs generated will be deep orcs on all levels except for the final level, where 4⁄5 of the orcs generated are deep orcs. The deep orcs generated on the fourth floor, The Halls of Moria, at level creation will always be hostile towards you.
Groups of deep orcs are very difficult to deal with through physical combat alone, and care must be taken to avoid letting them overwhelm you while thinning their numbers. Ray-based spells and attack wands, along with powerful area-of-effect measures, can turn the tides in your favor more quickly.