The Royal Corps of Halberdiers is a fictional British regiment from Evelyn Waugh's Sword of Honour trilogy. In the novel, the regiment is described as being composed of four battalions: The 1st (Regular Infantry) 2nd (Territorial Army), 3rd (Commandos), and 4th (Militia). The Corps is derived from Waugh's own experiences in the Royal Marines throughout World War II.
The Halberdiers are commanded by an officer called a 'Captain-Commandant' — a rank derived from the Corps's purported origins as the "Earl Of Essex's Honourable Company Of Free Halberdiers" during the reign of Elizabeth I (the halberd being a popular heavy infantry weapon of the time). The rank is analogous with Colonel.
References
Royal Corps of Halberdiers Wikipedia(Text) CC BY-SA