During this time, there were no big military operations in Europe. There was a British and French declaration of war on Germany, and military alliances between the Western Allies and Poland. The Royal Air Force dropped propaganda leaflets on Germany, and Canadian troops began to arrive in Britain. At sea, Britain and France blockaded Germany. German submarines destroyed many Allied ships, marking the beginning of Battle of the Atlantic.
In April 1940, Germany invaded Denmark and Norway. The two sides began to fight each other again. Britain and France needed a lot of weapons quickly, so they began to buy them from American weapon companies. The American government helped Britain and France by selling weapons at lower cost, and, later, lend-lease of military equipment and supplies.