Effects of microstructure and loading conditions on failure behaviors of polycrystalline ceramics are studied using phase field simulations. Ceramics produced by spark plasma sintering (SPS) are characterized at the microstructural scale and tested mechanically via quasi-static and dynamic bending and other techniques. Phase field simulations explore the role of bulk grain and grain boundary properties, residual stresses, and relative grain sizes of constituents. Materials consist of boron carbide with various fractions of titanium diboride. Also considered in theoretical simulations are effects of limited dislocation slip in titanium diboride and deformation twinning in boron carbide, where the latter has been noted in atomic scale calculations as a possible precursor to amorphization. Results of microstructure-scale simulations are compared to those from experiments as well as to results from a macroscopic homogenized phase field model accounting for viscous dissipation from micro-cracking. Insight into dominant material properties for upscaling to macroscopic models for ballistics is revealed.