John Gwynne was a 17th-century English author known for his military memoirs that provide a vivid account of the English Civil War and its aftermath. His notable work, 'Military Memoirs of the Great Civil War,' offers a firsthand perspective on the conflicts that shaped England during this tumultuous period. Gwynne's writings not only document military engagements but also reflect the political and social upheaval of the time, particularly through his account of the Earl of Glencairn's expedition in the Highlands of Scotland in the mid-1650s. Gwynne's memoirs are significant for their detailed portrayal of military life and strategy, as well as their insights into the loyalties and divisions that characterized the era. His work stands out as a valuable historical document, capturing the complexities of warfare and the personal experiences of those involved. Although not widely known today, Gwynne's contributions to military literature provide an important perspective on the English Civil War, enriching our understanding of this critical moment in British history.