I had a strange encounter with a reinforcing Pontic army in a KH campaign.

The battlefield was on the northern side of Byzantion, so it featured a large bay along the northern edge. I was deployed in the west facing a modest Pontic force. I rushed them (as far as you can with hoplites) and overwhelmed them before the massive reinforcing army could fully enter the map from the east.

Since the supporting army was arriving quite slowly, I ran my force to high ground in the south-east.

The Pontics, who were still marching to contact and hadn't yet formed a battle line started to wheel anti-clockwise to approach my new position. My force was outnumbered 3:1 and all my troops were exhausted - so I was expecting to go down Custer-style.

Then, amazingly, the Pontic army stopped dead! It was still deployed as a giant column (as if waiting to cross a bridge).

I waited until all my units were fresh, marched up to the lead unit and killed it. The rest of the Pontics didn't react. I was able to repeat this twice more before something in the Pontic formation came unstuck and they all started deploying - too late of course.

I've never seen anything like this before or since.