This work investigates the organizational structure, composition, and operational history of the New Model Army during the English Civil War. Sir Charles Harding Firth, a preeminent historian of the seventeenth century, utilizes extensive archival research and primary source documentation to reconstruct the formation and evolution of Cromwell's military forces. The text provides a rigorous examination of how the army functioned as both a political and martial entity during a period of significant national upheaval.

Historians and scholars of the English Civil War regard this text as a foundational reference for understanding the mechanics of seventeenth-century warfare. Readers frequently note the academic density of the prose, which serves as a definitive resource for those studying the professionalization of the British military.