Civilians
From Galactic Fleets Wiki
Civilians are the heart of you planet. Civillians pay taxes and increase your Fleet Funds. Civillians can grow depending on population and Civic Center upgrade. They are your power.
Although, they can rebellion or get disease. To prevent rebellion, you must keep your approval high. To increase approval, you must decrease your taxes. This would increase your approval rating. You can also increase approval rating by giving liquor to your civilians. But, if a rebellion is to rage out, you will require troops to calm the rebels down.
Disease are another threat. Your civilians makes food and water for themselves, creating extra food/water for the workers and troops. Those affected with the disease cannot make food and water, decreasing production. To solve this, you must have medicine made from a biofactory.
Although, diseases are not the only threat, there are plagues(advance version of disease, no report of plague.....yet), and the worst of all, zombies(very rare and never been reported before in V2...yet) Plague can be solved with medicine, but more quantity of it. Zombies would require mechs, troops, and medicine.
Now approval is a major part on your civilians. Approval is the happiness of your civilian. You can increase approval rating by lowering taxes and giving out liquor.
See Taxes
During an invasion, civilians can participate in invasions. Depending on the approval, a number of civilians will defend and fight against the aggressor. With 100% approval, 4 Civilians equals to a troop.
See Invasion, claiming, and taxes