Brandt’s Kneeling in Warsaw
Also called: Warschauer Kniefall, Warsaw Genuflection, Treaty of Warsaw (1970)
West German Chancellor Willy Brandt suddenly knelt before the memorial to the Warsaw Ghetto Uprising, a gesture of atonement for Nazi crimes; the same day he signed a treaty with Poland accepting its border.

Adrian Grycuk · CC BY-SA 3.0 pl · Source
On 7 December 1970, in Warsaw to sign the Treaty of Warsaw, Brandt laid a wreath at the monument to the 1943 ghetto uprising, then silently went down on his knees on the wet stone and remained there for about half a minute. The gesture had not been planned in the official programme.
By the treaty signed the same day West Germany in effect recognized the Oder–Neisse line as Poland’s western border. Some at home called the gesture excessive, but it went round the world as an image of Germany facing its past. Brandt received the Nobel Peace Prize the following year.