  The $(n,\gamma f)$ process is reviewed in light of modern nuclear reaction
calculations in both slow and fast neutron-induced fission reactions on
$^{235}$U and $^{239}$Pu. Observed fluctuations of the average prompt fission
neutron multiplicity and average total $\gamma$-ray energy below 100 eV
incident neutron energy are interpreted in this framework. The surprisingly
large contribution of the M1 transitions to the pre-fission $\gamma$-ray
spectrum of $^{239}$Pu is explained by the dominant fission probabilities of
0$^+$ and $2^+$ transition states, which can only be accessed from compound
nucleus states formed by the interaction of $s$-wave neutrons with the target
nucleus in its ground state, and decaying through M1 transitions. The impact of
an additional low-lying M1 scissors mode in the photon strength function is
analyzed. We review experimental evidence for fission fragment mass and kinetic
energy fluctuations in the resonance region and their importance in the
interpretation of experimental data on prompt neutron data in this region.
Finally, calculations are extended to the fast energy range where $(n,\gamma
f)$ corrections can account for up to 3\% of the total fission cross section
and about 20\% of the capture cross section.
