Detailed microstructural characterization was carried out on a commercial-grade hot-pressed boron carbide armor plate. The boron carbide grains have close to B4C stoichiometry, and most of them have no planar defects. The most prominent second phase is intergranular graphite inclusions that are surrounded by multiple boron carbide grains. Submicrometer intragranular and intergranular BN and AlN precipitates were also observed. In addition, fine dispersions of AlN nanoprecipitates were observed in some but not all grains. No intergranular films were found. These microstructural characteristics are compared with the lab-consolidated boron carbide and their effects on the mechanical properties of boron carbide are addressed.