  In this article we trace the genesis of a theorem that gives for the first
time examples of Galois group $G_S$ of the maximal $p$-extension of
$\mathbb{Q}$, unramified outside a finite set of primes not containing $p$,
that are of cohomological dimension $2$. The pro-$p$-group $G_S$ is a fab
pro-$p$-group which means that all its derived factors are finite.
