10 Darkest Star Trek Moments That You've Never Seen

What You Leave Behind features an unfortunate amount of re-used footage from earlier episodes, though remains one of the strongest series finales of any Trek series. While it is a busy episode, the retaliation, by the Dominion, against the Cardassian people is almost brushed over.

The Cardassian Union allied itself with the Dominion, inviting them to the Alpha Quadrant, all in the pursuit of regaining its former strength. This led to war, though as Weyoun so eloquently put it - they had become quite the disappointment. 

The Dominion never accounted for the sheer resistance that the Alpha Quadrant powers would put, but what's more, they certainly didn't expect it on their doorstep. The Cardassians, proud as they were, couldn't abide by the continuing disrespect offered to them by the Founders, the Vorta, and the Jem'hadar. The alliance with the Breen only solidified the resentment that had long been bubbling.

What began as various acts of sabotage against the Dominion became a full-scale uprising with the destruction of Lakarian City. The Cardassian fleet turned against the Dominion in battle, but the Cardassian people were left vulnerable. Though discussed in an almost off-hand manner, the retribution that the Dominion sought was terrible. As Bashir's stunned voice recounts - almost 800 million dead. 

Buildings are destroyed, bodies litter the streets, and the casualty reports were still coming in after the Female Changeling's surrender. This is one of the most horrific off-screen events in Trek history, even if we did see a tiny fraction of it as Martok takes his drink.