1. If you are talking about mobilization ('war-time mobilization' that is), the feature becomes available with Nationalism. On the F1 Domestic scrreen, instead of choosing "Normal" (the default), you can click the green button and select "War-Time", and every tile that produces at least one shield will produce an extra. So you can gain up to 21 shields (NOT including the factory, etc, bonus!
). However, you can only build military units (bombers, artillery, settlers, workers, etc, don't get the extra shield bonus applied to them) and military improvements (ie; no temple, cathedral, market, only barracks, walls, and some others. Some wonders you can build too). The button for this is by the button to change governments.