The Kalergi Plan

Wikipedia reports:

The Kalergi Plan, sometimes called the Coudenhove-Kalergi Conspiracy,[1] is a debunked far-right, antisemitic, white genocide conspiracy theory.[2][3] The theory claims that Austrian-Japanese politician Richard von Coudenhove-Kalergi, creator of the Paneuropean Union, concocted a plot to mix and replace white Europeans with other races via immigration.[4] ...

The conspiracy theory stems from a section of Kalergi's 1925 book Praktischer Idealismus ("Practical Idealism"), in which he predicted that a mixed race of the future would arise: "The man of the future will be of mixed race. Today's races and classes[a] will gradually disappear owing to the vanishing of space, time, and prejudice. The Eurasian-Negroid race of the future, similar in its appearance to the Ancient Egyptians, will replace the diversity of peoples with a diversity of individuals."[1][8] Modern far-right individuals seek to draw relationships between contemporary European policy-making and this quote.[1]

See, for example, Practical Idealism In Action - The Kalergi Plan.