Cybon was a competent and very able Astra Militarum commander who had a creditable history of Imperial victories over his long career. But like his contemporary, Hechtor Dravere, he was known to be predisposed to using the regular infantry as cannon fodder to achieve his tactical and strategic objectives. When the Warmaster Slaydo was mortally wounded during the fighting on Balhaut in 765.M41 and lay dying, Cybon was the strongest placed contender to serve as his successor as Warmaster, due to his seniority of command and long list of Imperial victories. Though Cybon possessed Slaydo's admiration as a leader, and expected the dying Warmaster's favour and support in the light of his victories during the Western Plains Campaign and at Ascension Valley, Slaydo despised Cybon's barbaric attitude towards the common soldiery.
When Marshal Macaroth was appointed as Slaydo's successor as Warmaster, Cybon was inflamed with rage at the decision, regarding the young officer as too inexperienced and too junior to command the Crusade. But Macaroth persevered and managed to hold onto the rank, outplaying his rivals politically, and indicating to all that he possessed the ideal talent and temperament for the role. When Macaroth began his campaign into the Cabal Salient in late 765.M41, many thought that the Warmaster was acting too boldly and overstretching his forces. Yet ultimately, most of the Crusade's senior officers, including Cybon himself to an extent, came to admire and respect Macaroth's tenacious ability to see paths to victory that other men could not.
In the years immediately following 773.M41, the Forces of Chaos attempted a major counteroffensive to reclaim lost territory, launching a pincer movement behind the advancing Imperial front at Macaroth's overstretched lines of supply and communication. By the 18th standard year of the Crusade the Imperial forces found themselves divided, hard-pressed and overstretched, fighting simultaneous actions right across the Khan Group and the trailward half of the Cabal Systems.
Up until that moment in the Crusade's history, the fighting had never been spread out across such a grievously wide front. Cybon complained in his personal journals that "Old Slaydo" would be appalled at how Macaroth had dismissed the traditional, methodical approach he favoured. By the close of 773.M41, the Crusade's advance had been broken, and the Warmaster's forces were in disarray. The fate of the Crusade hung in the balance at that point. By the close of 775.M41, as the Crusade entered its third decade, Imperial forces found themselves fighting a war on two fronts.
Macaroth charged Cybon with unifying and strengthening the flank of the Imperial advance and Imperial lines of support, a task he clearly despised. Cybon felt that he was a warrior and that his place should be at the front line of advance, not being sent to the rear to "mop up the dirt." In a communique to the Warmaster he complained incessantly of being relegated to such an unglamorous position and the grievous insult to his honour.
He asked if he truly had to continue to undertake such a menial task. Macaroth answered him bluntly the following solar day by responding with a single word, "Yes." Several of Macaroth's senior commanders soon found themselves charged with the prosecution of this Second Front, including Generals Van Voytz, Kelso, Bulledin, and Luswchiem, Marshal Blackwood, and the Lord Militant Humel as well as Cybon himself.
Their unpalatable task was to defend and push back the Chaos counterattack, but this meant they had to retake well-fortified enemy worlds that Macaroth had bypassed on his way to extending the Imperial salient deep into the Sabbat Worlds Sector. Cybon would be relegated to this position for the remainder of the Crusade, reluctantly following the Warmaster's orders to the bitter end despite his disdain for his mission and his commanding officer.
- Sabbat Worlds Crusade (Background Book) by Dan Abnett
- Tactica Imperialis, pg. 26