The Battle of Waterloo lasted roughly nine hours.  During that short time 37,000 men were killed or seriously wounded, and an estimated 20,000 horses. As the battlefield was small, it is possible that on June 19 a visitor could have walked across it without touching the ground.

The battle for Mosul lasted nine months, not nine hours. The loss of life at Mosul is appalling, and since future battles are likely to be in cities we can expect more of the same.  But in the longer view we have made some progress.