The regiment that the 6th Battalion, Ulster Defence Regiment grouped into had who as their oldest predecessor?
Royal Irish Regiment (1992) The Royal Irish Regiment (27th (Inniskilling) 83rd and 87th and Ulster Defence Regiment) (R IRISH) is an infantry regiment of the British Army. The regiment was founded in 1992 through the amalgamation of the Royal Irish Rangers and the Ulster Defence Regiment. Their oldest predecessor; the 27th Regiment of Foot; was first raised in June 1689 to fight in the Williamite War in Ireland. Other notable regiments in their lineage include the Royal Inniskilling Fusiliers, Royal Irish Rifles and the Royal Irish Fusiliers (Princess Victoria's).
East Yorkshire Regiment The East Yorkshire Regiment was a line infantry regiment of the British Army, first raised in 1685 as Sir William Clifton's Regiment of Foot and later renamed the 15th Regiment of Foot. It saw service for three centuries, before being amalgamated with the West Yorkshire Regiment (Prince of Wales's Own) to form the Prince of Wales's Own Regiment of Yorkshire in 1958. Subsequently, the regiment amalgamated with the Green Howards and the Duke of Wellington's Regiment (West Riding) to form the Yorkshire Regiment (14th/15th, 19th and 33rd/76th Foot) on 6 June 2006.