  Forward photoproduction of $\pi^+\pi^-$ pairs with invariant mass of the
order of $m_\rho\sim 770$ MeV is traditionally understood to be produced via
Pomeron exchange. Based on a detailed analysis of the CLAS photoproduction
data, it is shown that the dynamics of two-pion photoproduction for $|t|\gtrsim
0.5$ GeV$^2$ cannot be explained by Pomeron exchange alone. This motivates the
development of a new theoretical model of two-pion photoproduction which
incorporates both two-pion and pion-nucleon resonant contributions. After
fitting free parameters, the model provides an excellent description of the low
moments of the angular distribution measured at CLAS, and enables an assessment
of the relative contributions of particular production mechanisms and an
interpretation of the various features of the data in terms of these
mechanisms.
