The Krogan Rebellions began in the asari colony of Lusia. After centuries of unabated expansion, the krogan finally forced the Council's hand when they tried to annex this world. Aware that in a generation, Lusia could be a staging base for an invasion of Thessia, the Council came to the colony's defense. They cut the krogan supply lines off at Thessia's mass relay and inflicted heavy casualties. The krogan here surrendered, but others across the galaxy were enraged. Lusia became the catalyst for a much greater war.
More than a millennium later, Lusia finds itself once again in danger. Though the asari have lost the "high ground" of space, the colony's webbed defense grid remains at least partially functional. Land, sea, and air forces are striking wherever they can, determined to resist until the end.