271st Tank Brigade was formed shortly before the invasion on USA.
Back then it was equipped with newly designed AR-3 (Alexander Romanov-3) "Rhino" tanks (see "AR-3 Rhino" for more info)
They were in the first wave of invasion and spearheaded the assault on New York, Chicago, L.A. Washington and Norfolk. After the Philadelphia uprising, they started to be called "Bear Brigade", for their tactics.
Main doctrine of the 271st was straighforwarded attack, no hiding. Pure power and armor. And it was quite useful as they ironed with their tank about 1/3 of USA, leaving only burning hulks of their enemies forces.
Turning point occured about one year before the ending of the war, when they were caught in the Texas desert by US airforce. A group of about 40 Harriers II and 100 rocketeers turned 271st Brigade into a scrap metal in an hour or so. Their AA support was later found in the nearest city, having a camp. Commander of AA division was executed for incompetence.
Only 10% of the Bear Brigade survived the assault. Despite the traditional merging with other brigades, all survivors were sent back to motherland, and there, attached to the military and tank schools, where they've rised new generation of tankists.
After the war ended, they were assigned to the ITMO Design Bureau, where they've worked as testers and consultants on newly designed object 640 "Black Raven" tank. As a result they got tough tank, with more than average firepower, and which was more agile than AR-3 or any other old tank.
At the beginning of a new war, 271st Tank Brigade was formed again, consisting of old veterans, and new gifted tankists, rised by them. They were armed with the tanks they helped to developed.
Now they unofficially called "Raven Flock", although they utilize the same strategy as "Bear Brigade" and cary its pride further.