On the way to Port Arthur Historic Site on the Tasman Peninsula is Eaglehawk Neck, a narrow 30 metre-wide isthmus that join the peninsula to the rest of Tasmania.
This isthmus was once guarded by a line of ferocious dogs to prevent convicts escaping across the Neck from the nearby penal colony. The slightest disturbance would set the dogs barking and alert the soldiers. (There were dogs on platforms in the water as well).
The dogs were positioned JUST close enough that they could share a bowl of food, but far enough apart that they could not fight eachother.