A main battle tank of British origin, the Guardian became the mainstay of Allied forces on the ground worldwide after besting the Grizzly, an American-made design, in field tests across the board. While the Guardian's performance characteristics admittedly did not exceed those of the Grizzly by a wide margin, even a narrow victory was enough to justify switching production lines over to this newer model. After all, the Allied War Council fully expected to have to deploy Guardians in bulk in order to stave off Soviet armor divisions, believed to be the strongest in the world. To that end, the Allied Guardian Tank has proven to be something of an underdog, effectively helping to repel larger Soviet forces while bolstering the combat-effectiveness (if not the morale) of coalition forces caught in the same struggle.
You can read the full article, along with a short video of this unit in action here, at RedAlert3.com.