  We study the three-nucleon force in chiral effective field theory with
explicit Delta-resonance degrees of freedom. We show that up to
next-to-next-to-leading order, the only contribution to the isospin symmetric
three-nucleon force involving the spin-3/2 degrees of freedom is given by the
two-pion-exchange diagram with an intermediate delta, frequently called the
Fujita-Miyazawa force. We also analyze the leading isospin-breaking corrections
due to the delta. For that, we give the first analysis of the delta quartet
mass splittings in chiral effective field theory. The charge-symmetry breaking
three-nucleon force due to an intermediate delta excitation is small, of the
order of a few keV.
