  We report on a high-statistics measurement of the most basic double pionic
fusion reaction $\vec{n}p \to d\pi^0\pi^0$ over the energy region of the
$d^*(2380)$ resonance by use of a polarized deuteron beam and observing the
double fusion reaction in the quasifree scattering mode. The measurements were
performed with the WASA detector setup at COSY. The data reveal substantial
analyzing powers and confirm conclusions about the $d^*$ resonance obtained
from unpolarized measurements. We also confirm the previous unpolarized data
obtained under complementary kinematic conditions.
