Blackout

A blackout is the loss of the electricity supplied to a certain area.

During the Dominion cold war, Admiral Leyton ordered Red Squad to sabotage the global power grid on Earth, causing the whole planet to suffer a blackout. 

Throughout the Battle of Cardassia, the Cardassian Rebellion sabotaged Cardassia Prime's communications, transportation and power systems, causing a planet-wide blackout. This disabled the Female Changeling's ability to command the Dominion ships during the battle, ultimately resulting in the allies' victory. 

Memorable Quotes
"It's dark."
 * - Crewman Celes