We present a novel framework for spatial routing through difficult terrains with possibly untrustworthy regions in tactical mobile ad hoc networks. We describe a protocol, named "Reliability Map Routing" (RMR), which uses end-to-end Quality of Service metrics that include spatial reliability and trust. The RMR protocol reactively discovers routes over spatial cells whose local reliabilities are distributed throughout the network via a fast dissemination algorithm. By using a spatial approach where reliability and trust are attributed to space rather than to nodes, RMR is able to find reliable routes that persist for longer durations than those discovered by node-centric protocols. Furthermore, RMR is capable of reliable geocasting with low overhead. Via QualNet simulation studies, we compare the performance of the RMR protocol in terms of packet delivery ratio, delay, and overhead, and quantify the effects of node density, velocity, and traffic load on protocol performance. Our results indicate that the RMR protocol performs well in high mobility, high density scenarios because of its controlled routing overhead and spatial approach to routing.