  We classify nilpotent pre-Lie rings of cardinality $p^4$ and thereby braces
of the same cardinality, for a sufficiently large prime $p$. It has been shown
that nilpotent pre-Lie rings of cardinality $p^n$ correspond to strongly
nilpotent braces of the same cardinality, for sufficiently large $p$. These
braces are explicitly obtained from the corresponding pre-Lie rings by the
construction of the group of flows. Not right nilpotent braces of cardinality
$p^4$ have been classified, hence our results finish the classification of
braces of cardinality $p^4$.
