The celebrations commemorating the 75th anniversary of the WWII outbreak started in the Polish seaside city of Gdansk on Monday.
Polish President Bronislaw Komorowski, German President Joachim Gauck and Polish Prime Minister Donald Tusk participated in the event.
The traditional ceremony began at 4:45 local time (0245 GMT) in the morning under the Monuments of the Defenders of Westerplatte, a peninsula on the Baltic Sea, where the first events starting WWII began. The commemorating events include the call for a memory of the fallen soldiers, fire salute and placing wreaths.
In the afternoon, both presidents will lit candles at the Cemetery of the Westerplatte Defenders and take part in a special evening emission of Andrzej Wajda's war-themed play "Outbreak".
During the celebrations, Tusk said that "Here, at Westerplatte, saying 'no more war' today, we need to say it in full voice, together with our allies, that it will not just be words, it will be a wise policy, it will be a real European solidarity, a wise and courageous common strategy across the Atlantic."
He also called for European and transatlantic solidarity to take practical dimensions.
The attack of the German battleship "Schleswig-Holstein" on Polish military storehouse at Westerplatte on Sept. 1, 1939 was one of the first events starting WWII. Polish troops under the command of Major Henry Sucharski, defended heroically facilities against enemy attacks from the sea, land and air until the Sept. 7, 1939. Enditem