I'm not able to finish this mission.
I have build the 10 warships and 20 ferries fully loaded with bowmen and swordsmen. All 30 units is sailed to the south wast near the 3 spies I had there from the start.
As I read the mission brief this should be the only task.

The south west island is not accessible due to rocks in the sea shore!
Do I have to do something with the spies/thieves ?
Do I need to bring in a specific part of the map to my territory ?

If my memory from days now gone by is correctI recall correctly such finish task glitches have always been present in settlers 4. Have any of you finished this mission ?

Help is appreciated before I continue with other mission