  We analyze the longest-range two-pion exchange contributions to the
three-nucleon force at leading-loop order in the framework of heavy-baryon
chiral effective field theory with explicit $\Delta(1232)$ degrees of freedom.
All relevant low-energy constants which appear in the calculation are
determined from pion-nucleon scattering. Comparing our results with the ones
obtained in the $\Delta$-less theory at N4LO, we find effects of the $\Delta$
isobar for this particular topology to be rather well represented in terms of
resonance saturation of various low-energy constants in the $\Delta$-less
approach.
