This is a very new event introduced into the game this month.
This is how to score. Higher level of fortification will earn us higher score.
Just click on a capital to open the above menu and click up arrow for the meant activity.
Here is the capital fortification menu where the materials needed and the fortifications that could be executed is further detailed.
We need to deplete resource tiles completely to collect the materials needed for fortification. I am not sure if the number of materials found correspond to the number of resource depleted. I looked for smaller resource tiles first.
Oke guyz, happy fortifying. 😎😎