Riots on …

Stoking anti-government sentiment, The Returners are calling on the various species in our empire to return to their roots. Fighting has broken out between the movement's most extreme factions and pro-government forces. Severe damage has been reported in several major urban centers.

The command below will trigger the "Riots on …" event in Stellaris:

When this event fires, you can choose between the following option:

• Declare Martial Law
  • Gain modifier: Martial Law

Stellaris events fire in chains — one event leads to the next. Here is how Riots on … (origin.5004) connects.