What do the 'Seven Days to the River Rhine' refer to?

Seven Days to the River Rhine was a top-secret military simulation exercise developed in 1979 by the Warsaw Pact. It depicted the Soviet bloc's vision of a seven-day nuclear war between NATO and Warsaw Pact forces. This possible World War III scenario was released by the Polish government following their election in 2005, in order to 'draw a line under the country's Communist past', and 'educate the Polish public about the old regime'.

The scenario for the war was NATO launching a nuclear attack on Polish cities in the Vistula river valley area in a first-strike scenario, as well as Czech cities, which would prevent Soviet bloc commanders from sending reinforcements to East Germany to forestall a possible NATO invasion of that country. The plan expected that as many as two million Polish civilians would die in such a war and Polish operational strength would be completely destroyed.

A Soviet nuclear counter-strike would be launched against West Germany, Belgium, the Netherlands, Denmark and North-East Italy. Vienna was to be hit by two 500-kiloton bombs, while Vicenza, Verona, Padua, and several bases in Italy were to be hit by single 500-kiloton bombs. Hungary was to capture Vienna. Stuttgart, Munich, and Nuremberg in West Germany were to be destroyed by nuclear weapons and then captured by the Czechoslovaks and Hungarians.