Ok, I've played several campaigns as the English, but I've never actually seen the spikes Longbowmen can deploy be useful for anything.

Maybe I'm doing something different? Should I be deploying my longbows in front of my infantry, and using spikes to shield them some?

What happens when enemy units cross spikes? Will anything happen to my own units if they cross them?

Stupid questions I know. I should have a clue by now regarding these. I've just never bothered to use them as they didn't fit into my plans.