Joshua 11: Justifying Genocide?

Some people are troubled by the idea of the sun and moon standing still in Joshua 10.  Others are even more troubled by God's command to wipe out entire cities like we find in Joshua 11, among other places.  What are we to make of the Bible's apparent justification of genocide?
"And they put to the sword all who were in it, utterly destroying them; there was no one left who breathed, and he burned Hazor with fire" (vs. 11).  That is a pretty horrific description of the activities of Joshua's men.  "Genocide" means the deliberate killing of a large group of people, especially those of a particular ethnic group or nation.  Are we to believe that was God's will?

One argument that could be advanced in defense of the Israelites is that this was war, and that anything the Israelites did to the Canaanites et al would have been visited upon them instead had they lost.  What appears to be cruel on the surface may in fact be a matter of self-defense.  This was going to happen no matter what; it is just that Israel prevailed so that they were the ones who slaughtered rather than the ones who were slaughtered.

However, while this may be true, there is also more going on here.  It was apparently the Lord's intention to completely crush and wipe away the inhabitants of the land to make room for Jacob's descendants.  "For it was the Lord's doing to harden their hearts so that they would come out against Israel in battle, in order that they might be utterly destroyed, and might receive no mercy, but be exterminated, just as the Lord had commanded Moses (vs. 20).

It is important to keep in mind the total evil that infested the Promised Land before the Israelites reached it.  From violent bloodshed to abhorrent practices like child sacrifice to corrupt religious practices like temple prostitution, the inhabitants of Canaan had brought the judgment of God down upon themselves.  They had become devoted to destruction.  Their complicity in their fate should not be overlooked or forgotten - 400 years previously God had spared the people living there because their wickedness had not yet reached the proportions that would call for such extreme judgment (Genesis 15:16).

I find it ironic that some people accuse the Bible of holding a naive, idealistic view of things - while at the same time bothered by the savagery and brutality they find in its pages.  To me, passages like this show the Bible's realism about evil in the world, and about how the God of the Bible is intent on bringing that evil to an end through judgment.

On top of all this, there are surely those who would find the most upsetting aspect of this chapter to be the devastation wrought upon the horses mentioned: "And Joshua did to them as the Lord had commanded him; he hamstrung their horses, and burned their chariots with fire" (vs. 9).  Animals are not spared the consequences of living in a fallen world.  Neither are we.