The Great Panic began at the start of 2618, when Jason Zackaria's broadcast of his intentions to invade the Independent Worlds were followed up by the Pandoran fleet's arrival in many of the systems.

The panic led to hundreds of millions of people fleeing planets and star systems, and retreating from the Pandoran fleet that was gradually making its way towards the Helios Confederation. The panic led to much infighting, treachery and falling out between nations that were at one time stable and maintained good relationships. Loyalties disintegrated, and the allied forces were not only outnumbered and outgunned, but also defeated in battle due to a lack of cohesion between those battling the Enemy.

Essentially, two categories of peoples emerged - those that chose to run and those that chose to fight. However, there were also many who chose to surrender (or at least attempt to do so). Attempts at surrender were never accepted by the Pandorans, who killed any who came near the fleet and assimilated their ships into their ranks.

The Great Panic allowed the Pandoran army to sweep the galaxy and conclude many engagements in record time. Had the nations not panicked and bonded together to stand and fight, the Pandoran army might not have reached Sol in seven years, and may not have even reached Helios before the nanomachines began to breakdown and the soldiers started to die of cancer.