the ulster defence regiment (udr) was an infantry regiment of the british army established in 1970, with a comparatively short existence ending in 1992. raised through public appeal, newspaper and television advertisements, their official role was the "defence of life or property in northern ireland against armed attack or sabotage" but unlike troops from great britain they were never used for "crowd control or riot duties in cities". it was the largest infantry regiment in the british army, formed with seven battalions plus another four added within two years.