So how did the fighting progress?
As a whole, badly! The East Germans we were supporting were not regular army for the most part, but a mix of Grenztruppen and Kampfgruppen der Arbeiterklasse (Border Guards and Combat Groups of the Working Class, aka Communist Party militia, respectively). Nobody had thought West Berlin would be that difficult, so they delegated it to the East Germans...and the East Germans made a hash of it.
Their units were constant discipline problems. Looting and rape were common, and it took shooting a few of their officers and NCOs to get them moving again. The East German regulars, when we worked with them, were far better behaved. And NATO, they knew who they were facing, and took shameless advantage.
How so?
They would often booby trap stores they knew the stupid party hack bastards were sure to loot. I once saw a massive bomb take out a grocery store and most of a company of Kampfgruppe men. The survivors were screaming and some were still on fire, one was screaming how he was blind, and wanted someone to find his legs, because he couldn't feel them anymore. Christ, things like that stay with you, Comrade Professor, they stay with you. But all of this was nothing compared to what came next.
So what was the 21st like for you?
It began like the last 5 days in Berlin had, losing an average of a tank a block, getting T-55s as replacements, and finding out nobody had either a) trained on T-55s, nor b) had trained as loaders. We had about 12 tanks left, including the replacement T-55s. By noon, we'd lost 5 vehicles, and a good chunk of their crews. You could mark the progress of the advance by the wrecks left behind us. We'd barely made it more than a few kilometers into West Berlin. The motor riflemen hadn't had it any easier, and in some cases, they refused to ride inside their BMPs, calling them "a coffin for 11 brothers". Jesus, it was a nightmare.
We didn't know about the Kassel-Echwinge exchange, at least, not until three hours after it occurred. By then, we knew by the detonations we were seeing in all directions. We could see the lights, like so many flashbulbs. We had a lot of gunners blinded that way...The blast waves shook a lot of buildings, and we lost a few men when a building came down on them. More, well, they committed suicide when they saw the last one. It was Karlhorst. Karlhorst was closest to us...and I knew at that point, my family was dead. I...I did things after that. Things I don't want committed to history. My deputy had to literally force me into my NBC suit. Every man should have some secrets, especially under such circumstances. (Major Volobriev began to cry at that point, and we stopped the interview for the rest of the day).