In September 1939, the Nazi war machine invaded Poland and World War II began. France and its Britain declared against Nazi Germany in 1939. The French army was in theory as strong as the German army. It had a vast Empire and a sophisticated arms industry. It had also established a series of fortifications along the eastern border of the country along Germany, known as the Maginot Line. The Line was designed to keep German forces out of France. Initially, France and Great Britain appeared to be a match for Germany.
However, in a period of weeks in the late Spring and Early Summer of 1940, it became clear that that France was woefully unprepared for the German onslaught. France suffered a humiliating defeat and was quickly occupied by Nazi Germany. Its failure was a result of a hopelessly divided French political elite, a paucity of quality military leadership, rudimentary French military tactics. On the battlefield France faced a vastly more prepared German army that utilized both more advanced weapons and sophisticated tactics. It was a mismatch. Read more at DailyHistory.org.