Red Friday was a conflict on Mars between the Terra Firma movement and the Terran Federation government.

Following the Strekkelan War, some refugees from non-human worlds were relocated to colonies in the Sol system, mostly to Mars and Titan. When the refugee ships landed on Mars, members of the Terra Firma movement attacked the alien refugees, leading to the deaths of eighteen and over one hundred wounded. The Colonial Government of Mars ordered the arrest of several Terra Firma members.

The resulting conflict led to Terra Firma turning to street preaching.