Dwarf's and Goblinoids

The Dwarf's were the only race to refuse to join the elves. Using their great underground cities it was next to impossible for the elves to force under their rule. 200 years prior to the Ending War the elves hatched a plan to deal with the dwarves. They bred a goblinoid army of immense size and sent them into the dark depths to fight them to the death.
This war continues to rage in dark places under the earth. Many of the greatest dwarven cities have fallen to the goblinoids and it seems that it will only be a matter of time before they take them all.
Many dwarves have grown tired of the endless battle and given up on retaking their homelands. Instead they have constructed new towns above ground in the mountains in the east. The endless fighting has seen the dwarven numbers drop dangerously low, another reason many have given up the fight.
The Goblinoids, however, seem to be growing endlessly in number and the ambition of some of the warlords is causing those above ground some concern. For now it seems they are happy to eradicate the dwarves from the under dark.
Many have speculated as to why, with the elves dead, the goblinoids continue to fight. Those that have tried to answer this question have never been seen again.