On this day in 1939 the Royal Armoured Corps was formed. This new Corps brought together the Royal Tank Corps (which was renamed the Royal Tank Regiment), and all the British Army Cavalry Regiments that had replaced their horses with armoured vehicles. Uniquely, the units that formed the RAC kept their own names, badges and traditions. The RAC acted as an umbrella organization, handling recruiting, training and operational standards. The RAC cap badge was mainly worn by soldiers in training units, although some front-line regiments did wear it. Within 6 months the new Corps was at war. Like the rest of the Army, it expanded massively. Existing Territorial Army Yeomanry Regiments joined it, as did newly formed Cavalry Regiments and Infantry Battalions converted to use armoured vehicles. It later absorbed the Reconnaissance Corps. The modern RAC comprises 8 Regular Regiments, 4 Reserve Regiments and the Household Cavalry Regiment, which operates as a unit of the RAC, but is not officially part of it.