The 1970th were the classic time of the conventional WWIII-scenarios. Well known on this board is John Hackets "the third World War", but there were many others, like from the belgium general Close. Mostly this scenarios show, like the WP-forces attack West-Germany with overwhelming superiority and reach the Rhine in short time. Even in Hackets "optimistic" version, were NATO wins at the end, the WP-forces reach the Rhine after three days. There is no or just a symbolic nuclear reaction of NATO, the war is won or lost through conventional weapons.
There are some good reasons, why such scenarios seemed realistic at this time. The WP-forces reached the peak of their strengh, because of Detente some westeuropean Nations were reducing their forces, NATO seemed to lose their technological superiority, the USA were demoralised because of Vietnam and Watergate, nuclear deterrence seemed more and more questionable. In the hindsight it seems, the USSR had actually a window of opportunity, were they actually could defeat NATO without risking an all-out nuclear war. What if they had take the chance?
Let assume Watergate became a lot messier and/or Breshnev dies earlier and is replaced by someone more ambitous.
So, in a summer of 1976 the USSR start their preparations. The plan is, that the soviet-troops in the GDR and CSSR attack West-Germany. The goal is not an all-out war to conquer West-Europe or to create an socialist united Germany, but simply to force West-Germany to accept dearmend and neutralisation. This, so the men in the Kremlin believe, would be enough the gurantee soviet domminance in europe. So the plan goes through. NATO sees the signs, but reacts to late. There is no complet surprise, so the NATO-forces made some preparations, but is not enough. NORTHAG collapse, after a couple of days the Soviets reach the Rhine. CENTAG is better, but still the US- and german forces must retreat to Frankfurt and Nürnberg. The americans fire a nuclears shell against the soviets. The Soviets are not impressed and nuke a westgerman air-base. USA is unsure how to react, the westgerman goverment is shocked and accept the soviet demands.
So know two questions:
1. Is such a secenario relistic for the timeframe of 1975-79 and
2. How would the world look like today if something like this had happend.