Gauss constructed a CGS system of units by considering the value of the permittivity of free space
$$ \epsilon_0 = \frac{1}{4\pi} $$
which makes Coulomb‘s law very simple by making $4\pi\epsilon_0=1$ giving rise to the electric field
$$ E = \frac{q}{r^2} $$
that is a charge $q$ creates an electric field of magnitude $E$ at a distance $r$.
Because speed of light c is just $(\epsilon_0\mu_0)^{-1/2}$, in Gaussian units we can find the permeability of free space as
$$ \mu_0 = \frac{4\pi}{c^2}. $$