After taking Helleron without a fight, the Seventh advanced west along the railway between that city and Sarn. The Queen of Sarn, meanwhile, had heard the results of the Siege of Tark and wished to engage the wasps in a field battle, where she believed that the ants discipline would let her army triumph. Artificers from both sides had been fighting a small battle of their own, trying to keep the railway running, or not, as the case may be. The armies met at the point where the tracks had been most recently broken.
The Sarnesh deployed their army in its usual blocks of infantry, with battle-automotives deployed behind and fixed wing aircraft ready to intercept the wasp heliopters. The forces of the Ancient League were split between the flanks, with ants there to pass on messages from the mind-link.
The Wasps put their Sentinels in the centre of their line, supported by spear-armed Medium Infantry to either side. Most of the rest of the army were Light Airborne, at the front and flanks. Heliopters, leadshotters and Lancers were set up in support.
The battle started with the Ants advancing in perfect unison, with the Mantids and Moths at the flanks moving forward slightly ahead. The Wasp response was to send the Light Airborne to break up the advance and outflank the line. The flanking forces were intercepted and repulsed by Leaguers, while the large wave along the front was shattered by volleys of Ant crossbows and turret mounted nailbows on the automotives.
Just before the lines clashed, the air forces engaged, with Sarn again coming out on top. Soon after engagement, the Light Airborne broke and started to pull back, while the Medium withdrew to avoid being surrounded. The Sentinels at the centre of the line held stalwartly, but this only led them to being overwhelmed entirely.
With nothing now between them and the fleeing enemy, the ants continued implacably to the rear areas, while one flank of Mantis broke ranks to chase after them. It looked like the day had been won.
At this point a train arrived and started to disgorge hundreds of Wasps: significant re-inforcements, but not really enough to swing the tide. But, when their new weapon, the snapbow proved powerful enough to stop an Ant charge in its tracks, the Sarn tacticians realised that they needed to pull back right now to find some way of dealing with this.
The broken wasps rallied, but two companies of rearguard and what was left of the Ancient League sacrificed themselves to ensure that all of the transport automotives and the rest of the Sarnesh army escaped.