Krogan Rebellions

From galactic saviors to an endangered species, the war ended not by sword, but by a plague.

The Krogan Rebellions mark the galaxy's most devastating miscalculation. Originally uplifted by the salarians two thousand years before the original Mass Effect trilogy, the krogan were weaponized to defeat the rachni in exchange for new habitable worlds. However, uncontrolled by natural predators or harsh environments, their population exploded within just two generations. Faced with a demographic crisis, the krogan forcefully extended their dominion, refusing to leave the asari world of Lusia and sparking conflict across Citadel space.

This war did not end with a traditional surrender but with a biological catastrophe. The turians eventually deployed the genophage, a genetically engineered weapon developed by salarian scientists that drastically reduced the krogan birth rate to just one in every thousand viable births. Once hailed as saviors of the galaxy, the krogan were transformed into a species facing slow extinction, leaving behind a legacy of betrayal that defines their relationship with the rest of the Milky Way civilizations.

Quick Facts

Outcome: Krogan Defeat and Genophage Deployment

Facts from the source article.

Background

Two thousand years before the events of the original trilogy, the salarians culturally uplifted the krogan, providing them with faster-than-light technology rather than letting them discover it themselves. Motivated by a desire to manipulate the krogan as soldiers against the rachni, who were winning a war against the Council, the salarians relocated the krogan to new worlds. Within two krogan generations, they defeated the rachni and committed genocide on the species.

As reward, the krogan received former rachni worlds and several planets in Citadel space, with their fallen honored by a monument that still exists in the trilogy's timeline. However, the salarians' gambit backfired when the krogan population exploded. Facing a crisis, they forcefully extended their dominion to other planets, founding a colony on the asari world of Lusia and refusing to leave. In response, the Council ordered the Spectres to strike at the krogan, sparking the Krogan Rebellions.

The turians eventually joined the war against them. The conflict continued unabated due to the krogan's high birth rate and physical resilience. The turians deployed the genophage, a biological weapon developed by salarian scientists. This forced the krogan to accept the turian terms of surrender.

Once central to the Citadel military, they were replaced by the turians and became a shadow of their former prominence, with only 1 in 1000 births being viable.