The tank was developed in much the same way as the Vindicator Siege Tank, and it is unclear in Imperial records which design was developed first or even if the Sabre was a variant of the Vindicator. In any event, it proved remarkably efficient in its role. Like the Vindicator, it was modified to carry a massive weapon in a limited-traverse mount on a heavily-armoured Rhino chassis. While Imperial records are incomplete, it is believed that the Sabre is largely responsible for the dismantling of the massed armour formations once used by the Astartes. Near the end of the Great Crusade, the Mechanicum initiated the field testing of a new type of energy weapon known as the Neutron Laser Projector. This massive weapon, whose origins lie in the Dark Age of Technology, was mounted upon a variant