The Battle of Helska (also known as the destruction of the Outer Rim fleet) was an early battle during the Sith Crusade.
Following the battle of Belkadan the Galactic Alliance Outer rim fleet found itself retreating from the pursuing Sith fleet. The Alliance commander, determined to make a stand, ordered the fleet to hold position above Helska and engage the Sith fleet when they jumped out of hyperspace.
When they finally did the Alliance fleet found themselves no match for the warship leading the fleet, and many Alliance vessels were instantly destroyed.
Before long the entire fleet was in disarray. The battle was over.