Barren Sea Tiles

[Bellringer]

I was fighting a war with no navy and my enemy landed 2 frigates and 2 galleons on my shore. I found that 5 sea tiles around where they landed were stripped of their resources and my citizens became unemployed and my city faced starvation. How is this possible? Only improvements can be pillaged, not the basic productive capacity. I had no sea resources and no work boat, only citizens working on the sea tiles. I was playing Monarch Cyrus.

 

[God-Emperor]

Not a bug.

He was blockading you. It's a thing that only ships can do (not all of them can do it, but most can) and it prevents the affected tiles from being worked and blocks trade routes. If you do it with a Privateer you also gain some money each turn you blockade a city.

 

[Bellringer]

Is there a special command for this - I don't see one - or does it happen automatically if he anchors there and I have no defence? It persisted for quite a few turns after he left, until I had launched some of my ships. He was able to move from one port to another and sweep my tiles clean - awful!