The Ifni War, sometimes called the Forgotten War in Spain (la Guerra Olvidada), was a series of armed incursions into Spanish West Africa by Moroccan insurgents and Sahrawi rebels that began in October 1957 and culminated with the abortive siege of Sidi Ifni.

The war, which may be seen as part of the general movement of decolonization that swept Africa throughout the latter half of the 20th century, was conducted primarily by elements of the Moroccan Army of Liberation which, no longer tied down in conflicts with the French, committed a significant portion of its resources and manpower to the capture of Spanish possessions.

The city of Sidi Ifni was incorporated into the Spanish colonial empire in 1860. The following decades of Franco-Spanish collaboration resulted in the establishment and extension of Spanish protectorates south of the city, and Spanish influence obtained international recognition in the Berlin Conference of 1884. In 1946, the region's various coastal and inland colonies were consolidated as Spanish West Africa.

Ifni was a Spanish province on the Atlantic coast of Morocco, south of Agadir and across from the Canary Islands.

It had a total area of 1,502 km² (580 sq mi), and a population of 51,517 in 1964. The main industry was fishing.

Spain's presence in the area can be traced to a settlement called Santa Cruz de la Mar Pequeña, founded in 1476. The Spanish were expelled from the area in 1524 by the Berbers.

In the mid-19th century Spain became interested in its lost medieval fortress in order to claim the southern part of Morocco, and for no clear reason Ifni was wrongly considered the most likely area.

The territory and its main town, Sidi Ifni, were ceded to Spain by Morocco on April 26, 1860, following a short war, but there was little Spanish presence until 1934, when the governor-general of Spanish Sahara took up residence. During Franco's dictatorship, the colony was made a Spanish province to stop United Nations criticism on decolonization.

After the "Forgotten War" (1957) almost all was occupied by Morocco. Spain returned it to Morocco on January 4, 1969, and the territory was reintegrated into the Moroccan region of Souss-Massa-Draâ.