Tau force Charion Gate

In early 02.019M42 the alliance forces were still outnumbered by their opponents and were holding on to a very long front. To the west, the forces of Randolf's second army were an ever present threat, while all along the north and east of their sector, a long and winding front lay between the tau and eldar forces and the forces under Iron Warriors' commander Greghaz and his "West Front".

The Tau would have preferred to pull back from Old Town to shorten their lines, but at this location they held an important warp beacon, helping to guide in reinforcements from Tau space, and while this could be relocated, it would have to be de-activated. In addition, the alliance were more concerned than ever with the dominion of chaos over the device chamber, and started laying covert multilayered plans to eventually wrestle the device, and then the entire planet, into alliance hands.

The strategy focused first on taking the device room and changing its alignment. Chaos having fortified the chamber was a setback, but the alliance began sending small teams of tau and eldar into the city in order to scout out ways to get into the device room without having to fight a long and bloody street war against both the imperium and the forces of chaos. To do this they needed to get into the catacombs under the city, and to do that, they needed control of one of the city's main gates.

The Charion Gate was the closest and easiest to take, and in early 02.019M42 tau pathfinder and stealth teams moved into the city, encountering little resistance until one of the pathfinder teams was located by an adeptus mechanicus skitarii patrol. A short but brutal firefight developed, in which the tau managed to drive off the imperial force. This gave the alliance time to consolidate their hold on the Charion Gate and begin investigating ways into the underground chambers of the vast city.