The problem with killing a bunch of dead natives other than the obvious permanent scarring on your soul and the potential for getting haunted by the guy from Poltergeist, is the animals. They get used to the daily human flesh buffet, and the mass graves of dead Sikh workers helped a pair of mane-less male lions develop a taste for people.
The future can't come quickly enough.
The Tsavo Man-Eaters terrorized the workers of the Kenya-Uganda railway for nine terrifying months.
How They Killed:
We need to be clear: These bizarrely skin-headed lions weren't protecting themselves, they were actively sneaking into camp at night, climbing into tents and dragging the sleeping workers away to their deaths. Those tents were like pistachio shells to the lions, except the nuts inside kept screaming and had families to support, and oh God that's the saddest thing ever.
Over the long months of the spree, the workers and their British managers tried every conceivable way to stop the lions: they sent out hunting parties (who were evaded or slaughtered); built gigantic fences made of fucking thorns; and set out traps, but none of it worked. The lions were just like, "Oh, thorns, I'm totes out of my element, I've never had to avoid them growing up in the fucking jungle," before murdering more sleeping workers. For months the lions dragged away and ate the railway workers, killing as many as 135 of them.