The Mouse That Roared (1959)

The Mouse That Roared
Comedy
The Duchy of Grand Fenwick decides that the only way to get out of their economic woes is to declare war on the United States, lose and accept foreign aid. They send an invasion force (in chain mail, armed with bows and arrows) to New York and they arrive during a nuclear drill that has cleared the streets.
Starring
Peter Sellers, Jean Seberg, William Hartnell, David Kossoff, Leo McKern, MacDonald Parke, Austin Willis, Timothy Bateson, Monte Landis, Alan Gifford
Directed By
Jack Arnold