Duke of Lancaster ' s Own Yeomanry The Duke of Lancaster ' s Own Yeomanry has its origins in the various troops of light horse raised in the eighteenth century in the county of Lancaster , the earliest of which was the Bolton Light Horse formed in 1798 . In June 1828 the Lancashire Corps of Yeomanry Cavalry assembled and by special act , the king , William IV , granted the title Duke of Lancaster ’ s Corps of Yeomanry Cavalry in 1834 , and the Sovereign , as the Duke of Lancaster , has traditionally been Colonel - in - Chief . The regiment sent mounted infantry for service in the Boer War as the Imperial Yeomanry , between 1900 and 1902 . World War I . In World War One the regiment formed three units the 1 / 1st , 2 / 1st , and the 3 / 1st . 1 / 1st Duke of Lancaster ' s Own Yeomanry . Formed in August 1914 , in Manchester , the regiment became part of the Welsh Border Mounted Brigade . It was then split up with RHQ and ' C ' Squadron joining the 23rd Division in April 1915 , after being briefly attached to the 1st Cavalry Division in late April to early May 1916 . ' A ' Squadron joined the East Lancashire Division ; then it moved to the 53rd Division while in Egypt on 29 January 1917 , and moved to XXI Corps Cavalry in Palestine in August 1917 ' D ' Squadron joined the 14th Division . On 14 May 1916 , all the units except ' A ' Squadron reformed in France , where together with ' C ' Squadron of the Surrey Yeomanry , they formed III Corps Cavalry . On 24 July 1917 they were dismounted and became G . H . Q troops . On 24 September 1917 , after infantry training , the regiment joined a battalion of the Manchester Regiment , which was redesignated 12th ( Duke of Lancaster ' s Own Yeomanry ) Bn , the Manchester Regiment . 2 / 1st Duke of Lancaster ' s Own Yeomanry . Formed in September 1914 , the regiment remained in the United Kingdom until July 1916 , when it converted into a cyclist unit and moved to Ireland in May 1918 . 3 / 1st Duke of Lancaster ' s Own Yeomanry . The 3 / 1st were formed in 1915 . It also remained in the United Kingdom until it was absorbed by the 6th Reserve Cavalry Regiment in early 1917 . World War II . During World War II the regiment was mobilised as horsed cavalry but in 1940 , it converted into and formed the 77th Medium and 78th Medium Regiments of Royal Artillery . The 78th went on to serve in Palestine , Syria and Italy as part of 6th Army Group Royal Artillery ( 6 AGRA ) . The 77th remained in Northern Ireland until early 1944 when it prepared for the invasion of Europe . Landing in Normandy on D Day plus 6 , it was attached to 8 AGRA and fought for the Odon Bridgehead and in the battle of the Falaise Gap . It also provided support for the Arnhem Operation " Market Garden " in September 1944 . Post war . In 1947 the Duke of Lancaster ’ s Own Yeomanry was reformed as an armoured regiment . Its role changed to reconnaissance in 1956 , when it was equipped with armoured cars , but on 1 April 1967 , it combined with the 40th / 41st Royal Tank Regiment . Two years later , the combined regiment was reduced to a cadre until 1971 when it was reformed as an infantry unit . On 1 April 1983 , it rejoined the Royal Armoured Corps as a home defence reconnaissance unit , being equipped with Land Rovers . The regiment disbanded as a result of the Options for Change on 1 November 1992 and units amalgamated with The Queen ' s Own Mercian Yeomanry to form The Royal Mercian and Lancastrian Yeomanry and formed ' D ' ( Duke of Lancaster ' s Own Yeomanry ) Squadron .