This page contains information regarding Star Trek: Strange New Worlds, and thus may contain spoilers.
The Second Civil War, later known as the Eugenics War and finally escalating into World War III, was a conflict that occurred on Earth circa 2026; it might possibly be better described as the beginning of a conflict that eventually came to be known as the Third World War.
The events leading up to this civil war began with protests against the United States Government regarding freedom and equality. These protests included political groups such as Black Lives Matter, speaking out against law enforcement agencies whose individual officers used violence against blacks and other people of color.
Other political players were the Donald Trump supporters, who often wore their red MAGA hats to rallies for Trump, including at the United States Capitol, and often protested against President Joe Biden, as many of them believed his 2020 election victory against Trump to have been a fraud.
By the year 2024, due to the increase in homelessness, Sanctuary Districts were a common sight in major cities across the United States. This led to even more civil unrest, particularly the Bell Riots. (DS9: "Past Tense, Part I", "Past Tense, Part II")
That year also happened to be the year that Doctor Adam Soong was looking over a file labeled "Project Khan," which was left over from a previous series of conflicts that involved Khan Noonien Singh and his followers. It stands to reason that Soong went forward with Project Khan eventually, as the Second Civil War eventually became known as the Eugenics War, before it finally escalated into World War III. (PIC: "Farewell"; SNW: "Strange New Worlds")