Between 1639 and 1655, Scotland was engulfed in civil war. While there were lulls and ceasefires which punctuated the conflict, this period represents one of the bloodiest and most troubled decades in Scottish history. The two opposing sides, the Covenanters and Scottish Royalists, fought for the soul and body of the kingdom within the wider, archipelagic theater of the British Civil Wars. For the first time, 'His Majesty's Loyal Subjects': The Scottish Royalist Armies of the British Civil Wars, 1639-1655 records in meticulous detail the various Royalist regiments and units from across the conflict. Utilising a plethora of primary sources, including swathes of archival material, the make-up of the Royalist armies is clearly laid out and analysed, providing an unparalleled insight into the composition and organisation of these forces. Orders of battle for all major engagements enable the reader to chart the involvement of individual units and officers, a feat which has previously proved difficult due to the nature of the surviving source material. As well as collating information from hundreds of sources, contextual information is provided to situate the reader and offer background to the units' histories. All entries are presented in chronological order and supported by a comprehensive narrative of events. The accessibility of this information will provide enthusiasts and family historians with previously unavailable insights into Scottish Royalist forces and the military history of the British Civil Wars, while also granting scholars an invaluable tool for future research.