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 ∆(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 ∆-less theory at N 4 LO, we find effects of the ∆ isobar for this particular topology to be rather well represented in terms of resonance saturation of various low-energy constants in the ∆-less approach.