  To study gapped phases of $4$d gauge theories, we introduce the temporal
gauging of $\mathbb{Z}_N$ $1$-form symmetry in $4$d quantum field theories
(QFTs), thereby defining effective $3$d QFTs with
$\widetilde{\mathbb{Z}}_N\times \mathbb{Z}_N$ $1$-form symmetry. In this way,
spatial fundamental Wilson and 't Hooft loops are simultaneously genuine line
operators. Assuming a mass gap and Lorentz invariant vacuum of the $4$d QFT,
the $\widetilde{\mathbb{Z}}_N\times \mathbb{Z}_N$ symmetry must be
spontaneously broken to an order-$N$ subgroup $H$, and we can classify the $4$d
gapped phases by specifying $H$. This establishes the $1$-to-$1$ correspondence
between the two classification schemes for gapped phases of $4$d gauge
theories: One is the conventional Wilson-'t Hooft classification, and the other
is the modern classification using the spontaneous breaking of $4$d $1$-form
symmetry enriched with symmetry-protected topological states.
