The Phoney War was a phase in early World War II in the months following the German invasion of Poland (September 1, 1939) and preceding the Battle of France (May 10, 1940). Although on 3 September 1939 Great Britain, followed by France, had declared war on Germany, neither side had yet committed to launching a significant ground attack in the West on the continent.
While most of the German army was fighting in Poland, a much smaller German force manned the Siegfried Line, their fortified defensive line on the German side of the French border. On the other side of the border was the Maginot Line plus British and French troops, but there were only some local, minor skirmishes. The British Royal Air Force first dropped propaganda leaflets, and later some bombs, on Germany, but western Europe was in a strange calm for seven months.
Elsewhere, from March 1940, the opposing nations clashed in Norway. In their hurry to re-arm, Britain and France had both begun buying large amounts of weapons from manufacturers in the USA following their declarations of war, supplementing their own productions. The non-belligerent United States contributed to the Allies by discounted sales, and, later, the lend-lease scheme of military equipment and supplies. It should be noted that in the 1930s, on a much smaller scale, private companies in Britain and the USA were also supplying Germany, without government sanction. Engines of a few German fighters were made in Britain and American raw materials were still being sold to Germany. German efforts to interdict the Allies' trans-Atlantic trade at sea would ignite the Second Battle of the Atlantic.