Simple rigid crack‐front propagation and the mechanism of double‐kink nucleation and spreading are analyzed in a periodic crystallographic potential‐energy field. For the analysis the classical Griffith model for crack propagation is superposed on the periodic energy field of the crystal lattice. The energy‐condition theory of the time‐dependent crack propagation is developed in terms of the absolute rate theory. A complete kinetics analysis is carried out for the description of the rigid and kinked crack‐front propagation rate over the consecutive energy‐barrier system of the crystal lattice. The rate is expressed as a function of the applied stress, temperature, the free energy of fracture, and the lattice parameters.