Question

when France sneezes the rest of Europe catches cold describe

Answer 1

Klemens von Metternich was refering to two important ways, France influenced the rest of the Europe

First was the French Revolution:

It inspired several European nations like Poland, Austria, Italy and Russia to fight against Monarchy.

Second was the Rise of Napoleon:

Napleon became a dictator of France and then put the entire Europe into trouble by engaging them in battles and wars, occupying their territories till he was greatly defeated in the Battle of Leipzig and finally in the Battle of Waterloo.

The meaning is simple: Greater changes in France have great impact on Europe sometimes in a good way but mostly destabilizing it.

Klemens von Metternich, was the Austrian Diplomat, and later Chancellor during this period and was the first hand witness and authority over the changes occurring during his times across the Europe. So, he used this metaphor rather in a negative sense. His personal life and ambitions were in a certain way ruined by these changes in the Europe, which were influenced by France. He was forced to resign in 1848.