The Campaigns conducted by the Spanish Army from 1909 to 1926 to pacify the Spanish Protectorate in Morocco are almost unknown in the US Army, and the scarce literature written or translated to English provides only a partial vision of them. The ideas that prevail the mainstream scholarship are the severe defeat of Spanish troops at Annual in 1921 and the influence the Protectorate could have had in the political life of the country This monograph provides a broader vision which, first of all, highlights that the Spanish armed forces not only achieved the pacification of the Protectorate in 1926, but administered it peacefully until 1956 in a remarkable example of Stability Operations. The key to achieve this success was the ability of the Spanish Army to learn how to adapt to the Moroccan scenario culturally, tactically, and technically. Most importantly, during the campaigns of 1921-1926 the Army devised the methods and instruments that would allow for the fruitful administration of the Protectorate until 1956. To reach this conclusion, the paper provides first the background information that shows the challenges of the task presented to the Army in 1909. The next two sections discuss some of the factors, usually overlooked, that constrained the performance of the Spanish military: the international implications of the Protectorate, the strategic goal to maintain control of the Straits of Gibraltar, and the failure of the Spanish Government to design a coherent and well supported National Strategy regarding the Protectorate. Section four explains the stability operations that the Army performed, within means and capabilities, at the same time that it was providing security and how civilian projects increased as resources became available. Section five studies those areas in which the army improved the most along the campaigns, namely fighting effectiveness, unity of effort, training and coordination, experience and professionalism, equipment and relationships wit