  The contact strength, adhesion and friction, between graphene and an
incommensurate crystalline substrate such as {\it h}-BN depends on their
relative alignment angle $\theta$. The well established Novaco-McTague (NM)
theory predicts for a monolayer graphene on a hard bulk {\it h}-BN crystal face
a small spontaneous misalignment, here $\theta_{NM}$\,$\simeq$\,0.45 degrees
which if realized would be relevant to a host of electronic properties besides
the mechanical ones. Because experimental equilibrium is hard to achieve, we
inquire theoretically about alignment or misalignment by simulations based on
dependable state-of-the-art interatomic force fields. Surprisingly at first, we
find compelling evidence for $\theta = 0$, i.e., full energy-driven alignment
in the equilibrium state of graphene on {\it h}-BN. Two factors drive this
deviation from NM theory. First, graphene is not flat, developing on {\it h}-BN
a long-wavelength out-of-plane corrugation. Second, {\it h}-BN is not hard,
releasing its contact stress by planar contractions/expansions that accompany
the interface moir\'e structure. Repeated simulations by artificially forcing
graphene to keep flat, and {\it h}-BN to keep rigid, indeed yield an
equilibrium misalignment similar to $\theta_{NM}$ as expected. Subsequent
sliding simulations show that friction of graphene on {\it h}-BN, small and
essentially independent of misalignments in the artificial frozen state,
strongly increases in the more realistic corrugated, strain-modulated, aligned
state.
