How was eugenics linked to the theory of evolution?

Eugenics is an attempt to directly influence the coarse of human evolution by artificially selecting the pool of breeding partners and the resultant offspring. In effect, the methods are little different from those used in the breeding of cattle. One can model the outcome of such an experiment by applying evolutionary theory, genetics, to the parameters of the experiment. Other than that, there's no real linkage between eugenics and evolutionary theory.