When the cloned Imperial general Malphuus escaped into the Galaxy, he eventually came to be a trusted advisor to the System Lord Khepri. In this position, he was able to convince Khepri to ally himself with Rogue Squadron against Sobek, with the intention of double-crossing them and destroying both enemies.
In actual fact, Khepri was betrayed too. The plan left Sobek captive and Khepri presumed dead, allowing Malphuus to step out of the shadows during the confusion that followed and claim both domain for himself.
Fooling the Goa'uld into thinking he was one of them and the former Eighth Imperial Fleet into believing he was once a general in their ranks, he formed the Imperial Union. Immediately after his rise to power, the Union focused on attaining advanced technology, but was dogged by both Rogue Squadron and the Triumvirate.
Unbeknownst to the Imperial Union, Sobek's fall had led his heir, Nefru, to unleash the Dukhang on the galaxy. Before their eventual defeat, the Dukhang tore through Imperial Union space. Subsequently, the Triumvirate was able to secure a large portion of .
The Imperial Union finally came to an end while attempting to capture Sobek's superweapon for their own use. Leading the fleet personally, Malphuus was presumed killed when the superweapon backfired, destroying the entire system. The Union fragmented, freeing its subjects for the first time in millennia.