forum.freeciv.org

In Civ3 exist mobilization mode of country. In this mode unit production is speedup, but you cannot built peaceful buildings.

I have quite different solutions. Increasing mobilization your units will gain combat strength (defense bonus?), but shields on each city will be wasted. Mobilization will be great to defend against fast invasion, but makes production of units/buildings harder, so it could be only short time solution.

This seems to be even doable with existing policies mechanism. Maybe worth including into the game.
Just to put some limit on the advantage we must make the policy unchangeable back until peace treaty is signed, as it is in Civ3. This is not yet realized (and very harsh in fact since late Freeciv games, both against AIs and humans, rarely have peace).