The initial engagement within the Sepan system, referred to as the First Battle, involved a raid conducted by forces loyal to Dimok against a Ripoblus convoy. This raid was disrupted by Imperial forces under the leadership of Admiral Harkov during 3 ABY.
Following the Aftermath of Hoth, the Galactic Empire aimed to suppress the ongoing Sepan Civil War, a conflict that had persisted for generations within the Sepan system. Admiral Harkov received orders to bring this civil war to a conclusion. His initial strategy involved halting a raid by Dimok forces targeting a Ripoblus convoy. The objective was to eliminate at least 25% of the Dimok strike team, allowing survivors to relay the message of Imperial involvement to their superiors. However, the Prophets of the Dark Side grew suspicious, instructing their initiate, Maarek Stele, to meticulously observe the situation. Conflicting reports suggested that the civil war was not as straightforward as it appeared. Furthermore, Harkov's performance had fallen short of the Emperor's expectations.
As the battle commenced, the Ripoblus convoy transmitted a distress call to the Imperial capital ship, the Protector, requesting assistance. Harkov issued an order for the Dimok strike force to cease their attack or face the consequences.
The Dimoks asserted that they were intercepting illicit war materials and could not permit the convoy to escape, warning against any interference that would result in them being fired upon. Harkov's forces, aided by the Imperial pilot Maarek Stele, successfully repelled the Dimok strike force by destroying a minimum of 25% of their ships. Despite driving off the Dimoks, Stele's actions confirmed the suspicions of both the Dimoks and the Order by uncovering Imperial weaponry aboard the Ripoblus Modular conveyor group Asbo. This discovery prompted the Protector to dispatch Transport group Epsilon to disable and impound the transport group for further investigation. The Ripoblus responded by deploying three Delta-class JV-7 escort shuttles, named Ayalam, Noerbo, and Yawnor, in an attempt to prevent the seizure. Ultimately, all three shuttles were destroyed, and the convoy was seized by the Imperial transports.
The Dimok forces communicated news of the Imperial intervention to their leaders. The Ripoblus leaders, enraged by the assault, resolved to retaliate by attacking a Platform known as Youst.
Simultaneously, the clandestine order was troubled by the revelation of Imperial weapons within the Ripoblus convoy, as there was no plausible explanation for how they could have acquired them. Unbeknownst to them, Harkov had been secretly selling the weapons for personal gain.
This particular conflict is depicted in the video game Star Wars: TIE Fighter. Specifically, it is the first mission of Battle 2. The primary objective for the player is to destroy at least 25% of the Dimok forces. The secondary objective involves inspecting the Modulor conveyor group Asbo. The secret objectives include ensuring the success of the capture operation and inspecting all primary Dimok starships.