On September 1, 1939 Germany invaded Poland. France had already guaranteed Poland's security, and as a result declared war on Germany two days later. Yet despite having what some contemporaries considered the finest army in the World, France's strategy was defensive and no help reached Poland. When Germany invaded in 1940 the French Army, previously only involved in some minor actions, was tested to the full and was unable to avoid occupation of their country - an occupation that was to last over four cruel years.