This training circular (TC) discusses the formation and alignment of Army bands and the marching band formations used by Army bands. FM 3-21.5 prescribes marching standards for Soldiers with or without weapons. TC 12-45 adapts selected movements of FM 3-21.5 to permit practical use of musical instruments in military formations. These adaptations conform to the best or most common ceremonial practices found in U.S. Army bands and in the Army ceremonial units that support the Military District of Washington. They are to be used only by officers, warrant officers, and Soldiers in Army bands while carrying musical instruments in marching band formations. In any formation where musical instruments are not required, Soldiers in Army bands will conform to the standards described in FM 3-21.5. This TC suggests principles of instrumental placement which band commanders can use to increase the musical effectiveness of the marching band- followed by an explanation of guide files and the responsibilities of band members marching in the guide files. This TC also addresses the stationary movements used by the band commander in conjunction with the marching band.