The Battleship That Started the War

Pre-Dreadnought Battleship Schleswig-Holstein in 1928.

On September 1st, 1939, this happened (via Wikipedia):

At the end of August 1939, Schleswig-Holstein sailed to Danzig, under the pretext of a courtesy visit, and anchored in the channel near Westerplatte. On 1 September 1939, at 4.45 a.m. she began to fire 280mm and 170mm shells at the Polish garrison there.^[1] The Battle of Westerplatte lasted seven days. After the capitulation of Westerplatte, the Schleswig-Holstein battered Gdynia, Kepa Oksywska, and the Hel Peninsula. During the bombardment of the last she was hit by a 152 mm shell from the Polish battery.

Schleswig-Holstein fires on Polish positions at the Port of Danzig on Sept 1, 1939.

 Fortunately, the war ended on a different Battleship, 6 long years later:

USS Missouri (BB-63) is anchored in Tokyo Bay, Japan, 2 September 1945, the day that Japanese surrender ceremonies were held on her deck.