During that time, there were no major military operations in Europe. The United Kingdom and French declared war and a blockade against Nazi Germany. Also, Germany did likewise by beginning the Battle of the Atlantic, and German submarines destroyed many Allied ships. The British Royal Air Force dropped propaganda leaflets on Germany, and Canadian troops began to arrive in Britain.
In April 1940, Germany invaded Denmark and Norway. Both sides began to fight each other strongly again. Britain and France needed many weapons quickly and so they began to buy them from American weapon companies. The Americans remained neutral but helped Britain and France by selling weapons cheaply and then by Lend-Lease of military equipment and supplies.