Abstract We perform a Feynman diagram calculation of the two-loop scattering amplitude for gravitationally interacting massive particles in the classical limit.Conveniently, we are able to sidestep the most taxing diagrams by exploiting the test-particle limit in which the system is fully characterized by a particle Trailer Hitch Wires propagating in a Schwarzschild spacetime.We assume a general choice of graviton field basis and gauge fixing that contains as a subset the Power Control Board well-known deDonder gauge and its various cousins.As a highly nontrivial consistency check, all gauge parameters evaporate from the final answer.Moreover, our result exactly matches that of Bern et al.
[39], here verified up to sixth post-Newtonian order while also reproducing the same unique velocity resummation at third post-Minkowksian order.