Westerplatte (Poland), Sep 1 (DPA) Polish leaders, veterans and the archbishop of Gdansk gathered before sunrise Tuesday on the Baltic coast to commemorate the moment a Nazi battleship fired its first shots at a military garrison Sep 1, 1939, to spark World War II.

'It was them that gave testimony of strength and heroism,' President Lech Kaczynski said of the 180 Polish soldiers on the Westerplatte peninsula who for a week defended the fort against dive-bombing raids and naval artillery.

'There is a question why Poles defended Westerplatte, why Poles did not take concessions (offered by Nazi Germany),' Kaczynski said. '... In Poland, we do not know the notion of peace at any price.'

The Polish leaders are to later be joined by Russian Prime Minister Vladimir Putin and German Chancellor Angela Merkel among the 21 heads of government who are slated to attend anniversary ceremonies.

Other guests include the prime ministers of Italy, France and Sweden, which currently holds the European Union's rotating presidency, for a day of ceremonies and meetings.

Westerplatte surrendered Sep 7, 1939, as the Nazis continued their attacks across the country.

The Soviet Union invaded from the east 10 days later in accordance with the German-Soviet Molotov-Ribbentrop Pact, in what Kaczynski called a 'knife in the back'.

'Westerplatte is a symbol,' Kaczynski said, 'of heroic resistance of those who are weaker against those who are stronger.