The Raid on Kohlingen took place approximately eight years ago in Final Fantasy VI, during the Second Gestahlian Campaign. Neither the identity of one of the belligerents, nor that of the victor, is ever made clear.
Kohlingen is part of the Kingdom of Figaro. According to a timeline, Figaro has been allied with the Gestahlian Empire since the latter conquered the western continent in the Second Gestahlian Campaign some 8 years ago. The raid on Kohlingen is the only battle of this war that is mentioned in-game, and its location could mean that the Second Gestahlian Campaign was, in fact, a war between the Gestahlian Empire and Figaro. Another hint of this is a riot that broke out in South Figaro after the alliance was proclaimed. However, it is never confirmed that the Gestahlian Empire and Figaro were at war.
Raid and aftermath
Kohlingen was largely destroyed in the raid and had to be rebuilt. Apart from this, the only known fact about the raid is that Rachel was killed in it. Her lover Locke Cole blamed the Empire for her death, and subsequently joined the Returners.