On September 1, 1939, at 0445 local time, as Germany began its invasion of Poland, Schleswig-Holstein started to shell the Polish garrison on Westerplatte near the city of Gdansk. The Battle of Westerplatte was the very first battle of the war. It lasted 7 days. 182 Polish soldiers fought 3,500 German soldiers.
Read more on Wikipedia: Battle of Westerplatte
Below you can see an authentic footage of the attack. (Audio is edited.)
