Histories tracing the evolution of the modern British navy nearly all begin their examinations of the fleet during the Cromwellian Protectorate or early restoration England of the mid-to-late seventeenth century. While such studies abound, few recognize the fundamental importance of the growth and restructuring of the navy during the English Civil Wars, beginning in 1642. In my study of the first year of the parliamentary navy I argue that the origin of the modern British Navy should be traced back a decade before the Protectorate to the civil war fleet and the first navy to be run by parliament rather than the king. Understanding that the men and vessels of the civil war navy are integral and overlooked progenitors to the fleets that followed them also highlights the importance of that navy to the origins and early military campaigns of the English Civil War. By more fully recognizing the centrality of debates surrounding the navy and how the successes and stresses of the fleet shaped the conflict between King Charles I and parliament in 1642-3 this dissertation connects the fleet back to other important wartime events in England and on the continent instead of examining it in the maritime vacuum in which it is so often considered. By integrating the civil war navy's history into the social, political, military and economic context of the English Civil War, my work shows how the context in which the civil war navy was funded and operated created a fleet that linked the Caroline and Protectorate navy. Furthermore, examining the war's evolution in the context of events related to the navy---instead of the other way around---I provide an additional angle to complement existing studies that consider why the war developed in the specific way it did through the summer of 1643.