Members of the German Football Federation paid their respects at the site of World War II’s opening battle on Wednesday.
It was a solemn occasion as the German delegation laid a wreath at the Westerplatte monument before taking a tour of the memorial.
Germany will meet Greece in the Euro 2012 quarter-finals on Friday at nearby Gdansk’s PGE Arena.
“If today German fans can wander around in Gdansk with German flags in their hands and they get welcomed kindly – Poland is even crossing their fingers for our team – then that is a great development, a peaceful development, if you consider what has happened here,” German Football Federation president Wolfgang Niersbach said.
“For this we should be grateful.”
The first shots of World War II were fired at Westerplatte when German forces attacked the Polish garrison in the early hours of September 1, 1939.
Significantly outnumbered, the Poles held out for seven days before surrendering.
“For the German FA and our team we regarded it as a duty to come here to Westerplatte and confront ourselves with what unimaginable things happened here over 70 years ago,” Niersbach said.
“Being German we have to confess to this. As a warning for the future this must never be forgotten.”
Germany, the only team to win all three of their group matches, will face either England or Italy in the semi-finals should they overcome Greece.