The division was established on August 20, 1943, in accordance with General Reserve Instruction No. 2 of the Central
General Staff of the
Spanish Army, on the basis of the previous
13th Division (
:es:13.ª División (Ejército Franquista)) part of the I Army Corps of Military Region I. It traces its name to the
Battle of Brunete during the
Spanish Civil War, which was the largest
tank battle in the
military history of Spain. Its origins can be found in the military restructuring after the civil war, in which five regiments of battle tanks were established that took advantage of the captured vehicles. Its first major general in command was
Ricardo Rada Peral, and the division was established at the
El Goloso Camp, in the
Sierra de Guadarrama. With the normalization of diplomatic and military relations with the United States in the mid-1950s,
M24 Chaffee and
M47 Patton battle tanks,
self-propelled artillery units, and a "heavy weapons" company joined the division. Between 1953 and 1968, the Spanish Army received a total of 446 medium battle tanks (M47s and M48s), 123 light tanks (
M24 Chaffees and M41s), as well as 30
M74 armoured recovery vehicles. In 1970, the United States agreed to extend the military aid program by another five years, giving Spain another 66 M48A2 tanks and 17 M41A3s. The division was reorganized in 1965 due to the new vehicles. This included the General Staff, based at
El Pardo, and the
Nucleo de Tropas Divisionario (Divisionary Troop Nucleus). The latter was formed by the
Villaviciosa Light Armored Cavalry Regiment, the Campaign Artillery Regiment, the 1st Anti-Air Artillery Group, Engineering Regiment No. 1 and the Divisional Logistics Group. There were two fighting brigades: Mechanized Infantry Brigade XI, which included the
6th Saboya Motorized Infantry Regiment, the 55th
Uad Ras Mechanized Infantry Regiment, the XI Self-Propelled Artillery Group, the XI Engineering Battalion and Logistics Group XI. The other was Armoured Brigade XII, which was made up of the 61st
Alcázar de Toledo Armoured Infantry Regiment, the
31st Asturias Mechanized Infantry Regiment, the XII Self-Propelled Artillery Group, the XII Engineering Battalion and Logistics Group XII. The
Alcázar de Toledo Armoured Infantry Regiment included most of the division's tanks, two regiments of 48 M48s and 54 M47s, respectively. == 1981 attempted coup ==