The Spanish Legion, founded in Morocco in 1920, has always been under the direct command of the chief of the army staff. It has had a reputation as the toughest combat unit in the service. Although modeled after the French Foreign Legion, it never acquired the international flavor of its French counterpart. Reduced in size to 8,500 in 1987, as a result of successive reorganizations, the legion was scheduled to undergo further cuts to an overall strength of 6,500. It had a higher number of career soldiers than other units, but it was manned mostly by conscripts who had volunteered for the legion. Recruitment of non-Spanish personnel, who had never exceeded 10 percent of the group's manpower, ended in 1986. Foreign legionnaires already in the service were not affected.

As of 1987, the Spanish Legion was grouped into four tercios (sing., tercio), a unit intermediate between a regiment and a brigade, each commanded by a colonel. The first and the second tercios constituted the core of the military garrisons at Melilla and Ceuta. Each had been reduced by a motorized battalion, leaving it with a single motorized battalion, a mechanized battalion, an antitank company, and a headquarters company. They were equipped with BMR armored personnel carriers. The third tercio, stationed in the Canary Islands, consisted of two motorized battalions and a headquarters company. The fourth tercio was being converted from a support role to a combat unit at the legion headquarters in Ronda near Malaga.

In 1987 the Ministry of Defense was planning the creation of a rapid deployment force composed entirely of volunteers. This force, which would include the Spanish Legion, the paratroop brigade, the airborne brigade, and Marine units, would be available for use in trouble spots on twelve hours' notice. Lack of adequate air and naval transport would, however, be a limiting factor.

Data as of December 1988