Willy Brandt came to Warsaw on December 7, 1970 to sign a treaty which - later known as the "Warsaw Treaty" - initiated diplomatic relations between the two states and, above all, recognized the Polish western border.
With this, the Bonn social-liberal coalition took a step in its Ostpolitik, while communist Poland had many opportunities for increased cooperation with the West.
Brandt's kneeling on that day was an unexpected and strong sign: in a symbolic act he also commemorated the victims of Poland in the war, the Jewish victims and their desperate struggle, and he acknowledged German responsibility for Hitler's crimes.