Siege Tank

The siege tank was a terran armored vehicle that could be configured to fulfill both the mobile combined-arms support role and the long-range artillery support role. Developed by the Terran Confederacy and carried forward through the Terran Dominion and the wider sector, the siege tank's defining feature was its ability to transform on the battlefield between a conventional tank and a static emplacement deploying a far more powerful cannon.

Concept and modes#

The dual-mode siege tank concept was a Confederate response to the flexibility of the goliath walker. Before the Guild Wars, work had progressed on a static "final defense" cannon, but the conflict demonstrated the need for mobility, and an effort was made to render the cannon mobile. The solution modified an existing tank design so that it could operate as a conventional tank and also deploy the cannon to become a static artillery emplacement at will. Mobile siege tanks existed by 2480, several years before the official start of the Guild Wars, and an artillery version was in Confederate use during that conflict.

In its "tank" or "assault" mode, the vehicle served in the familiar armored support role using relatively light weapons. In the more radical "siege" mode it became a static emplacement deploying a much more powerful and longer-ranged weapon. The tradeoff between mobility and firepower defined siege tank doctrine across every terran force that adopted the design.

The AAV-5 Arclite#

The AAV-5 Arclite was in service by 2491 and was renowned throughout the Confederacy for its heavy firepower and its stalwart emplacement-and-advance tactics. It carried a crew of three, a gunner, a driver and a commander, though a single operator could still run it. The Arclite could double as a sort of armored personnel carrier, ferrying troops into a hot zone and deploying them through side and rear hatches. A gravity accelerator kept it stable in low or zero gravity, hydraulic actuators steadied it even under explosive fire, and its gyros let it climb inclines of up to sixty-five degrees. A targeting computer keyed on heat sources, identified their range, and could render the surrounding topography in three dimensions on an interior viewscreen.

The Arclite carried twin 80mm PPG-7 plasma cannons when mobile and a 120mm Shock Cannon in siege mode, later upgraded to the 120mm Mjolnir Artillery Cannon, which fired plasma shells in place of the standard explosives and was sometimes used for scorched-earth operations. By the aftermath of the Great War the AAV-5's tank mode left much to be desired: its armament and armor were too light to advance or hold a firebase against a close assault without significant support. The Crucio was developed to address those shortcomings.

The Crucio#

The Crucio was designed as the AAV-5's replacement and had entered Dominion service by 2502. It featured superior protection and armament, with an enlarged, reinforced turret and hull built for survivability, and an upgraded tank-mode weapon package that let it defend itself in open battle. Its treads were modular heavy-duty neosteel plates in a multi-track configuration, with extra tracks for stability and a system of tubes that pumped fast-drying gel onto damaged segments so the tank could keep moving after damage that would immobilize a conventional vehicle. In siege mode the main tracks turned outward, the secondary tracks slid into the hull, and thick hydraulic outriggers deployed from the sides to brace the roughly sixty-ton vehicle against the ground.

The Crucio's turret mounted twin 90mm plasma cannons in assault mode, effective against enemy armor. Its true strength lay in siege mode, when those cannons became the 180mm Shock Cannon, a weapon whose roar alone was said to send enemies of the Dominion into full retreat. The Shock Cannon fired superheated tungsten across an area larger than the older 120mm version and could load a range of munitions, including armor-piercing Maelstrom shells. Dominion infantry were nonetheless universally convinced that Crucio operators inflicted more damage on friendly forces than on the enemy, and LarsCorp developed a "smart shell" that scanned for allies on impact and adjusted its detonation, reducing friendly-fire fatalities by seventy-five percent in field tests. During the reign of Valerian Mengsk, the Dominion improved the Crucio with reinforced plating and heftier cannons for the Special Forces.

Other models and service#

The Umojan Protectorate developed its own siege tank, the Imperio, a recent invention that already rivaled its Dominion counterparts in early combat tests, which had been precisely the design goal. By the Defenders of Man Insurgency the Protectorate was also operating Crucios, a number of which were infested by the zerg on Jarban Minor. Mercenary groups were known for heavily modifying their siege tanks to increase functionality and to make them more visually intimidating, while Tyrador IX maintained platinum-alloy siege tanks to fire ten-round salutes for visiting dignitaries of sufficient rank. During the End War, Nova Terra deployed advanced heavy siege tanks against Amon's forces.