During the Norwegian campaign in 1940 the Norwegian Army lacking suitable anti-tank weaponry had to rely on petrol bombs and other improvised weapons to fight German armor. Instructions sent to army units in April 1940 from Norwegian High Command encouraged soldiers to start ad-hoc production of "Hitler cocktails" (a different take on the Finnish nickname for the weapon) to fight tanks and armored cars. During the campaign there were instances of these petrol bombs being quite effective against the lighter tanks employed in Norway by Germany, such as the Panzer I and Panzer II.