The battle that set off the Peacekeeper/Scarran War occurred around 60 solar days after the destruction of the wormhole to Earth and the crystallization of John Crichton and Aeryn Sun. It was the culmination of several years of rising tensions in the cold war between the Peacekeepers and the Scarran Empire.
A Peacekeeper armada under the command of Scorpius ambushed a convoy of Scarran dreadnoughts in orbit of a ringed gas giant. Using the planet's rings as cover, the fleet of command carriers was able to surprise the dreadnoughts, launching Prowlers and Vigilantes and destroying a dreadnought in the opening salvo as the Scarrans scrambled to defend themselves. Though the Scarrans were able to launch Strykers to meet the harassing Prowlers led by Captain Braca, the Peacekeeper forces were clearly closing on victory.
This would change, however, when Scorpius suddenly and inexplicably ordered his carrier's retreat and withdrawal from the battle in spite of his officers' protests. Without Scorpius' carrier to fulfill its vital role, the Scarrans were able to rally their own forces and win the battle.