Complex sentence: During World War I there were a further two Courts-Martial: the Regimental Court-Martial (RCM), which rarely sat; and the Field General Court-Martial (FGCM).
Split into simpler sentences: During World War I there were a further two Courts-Martial. The Regimental Court-Martial (RCM), which rarely sat, and the Field General Court-Martial (FGCM).