Morocco was an independent state (and notorious pirate haven) when European imperialist powers set upon it in the late 19th century. The stiffest resistance to colonization was offered by Berber tribesmen: descendants of North Africa's original inhabitants, who once ruled all the land between Morocco and Egypt. Making zealous converts to Islam after the Arab invasion, Berbers were largely responsible for the conquest of Spain in 711. This time around, however, their effectiveness was crippled by ethnic strife and the tenuousness of tribal alliances. By 1912 most of Morocco was a French protectorate. Spain controlled the northern fifth, owing much to a British wish of insulating Gibraltar from the French.

Yet the inhospitable Rif mountains, whose particularly defiant Berber tribes had only nominally acknowledged the Sultans of Morocco, remained unoccupied. When this was rumored to change in 1919, the Spanish-educated Abd al-Karim (1882-1963), a disillusioned former functionary in the colonial administration, began uniting the tribes against the invaders. The sophisticated al-Karim was helped by his brother Mohammad, a rousing military leader.

In July 1921 Spanish troops under the command of the adventurous General Manuel Fernández Silvestre crossed the Amekran River despite warnings by al-Karim that this would be considered an act of war; supposedly, the General laughed at this notification. By mid-afternoon they were surrounded by Rifi. After five days of siege, several hundred Spaniards were killed and the rest expelled at the cost of 8 or 9 Berber irregulars. This launched a fierce guerrilla campaign of raids, ambushes, and attacks on overextended supply lines. In three weeks, 3,000 Berbers armed with outdated flintlock rifles killed more than four times as many Spaniards as the Americans have lost during two years of war in Iraq. An additional 13,000 fled in panic, leaving behind enough cannons, guns, ammunition, and other gear to equip a minor army. The 'disaster of Annual' remains one of the most throroughly repressed events in 20th century Spanish history, and conversely, one of the most celebrated in North Africa.

The smell is terrible as the Spanish Foreign Legion enters Nador town on September 18, 1921, after the disaster of Annual.

Still aided by his loyal brother, Abd al-Karim proceeded to seize the entire Spanish zone, except a few coastal outposts such as Ceuta and Melilla, and control it for about five years. On February 1 1923 he proclaimed the Republic of the Rif, a constitutional state with a formal administration. A modern army of 80,000 men was created, complete with machine guns, howitzers, and hired defectors from the French Foreign Legion. Abd himself held the title of Emir, refusing that of Sultan.

It was the intervention of the increasingly worried French that would spell the doom of the Rif Republic. When they advanced on the Berbers, the latter chased them back almost as far as Fez. But in 1925 the French and the Spanish joined forces - some 235,000 in total - to finish off the rebels. The cast of characters is remarkable; the French commander being none other than Marshal Henri Phillippe Pétain and the leader of the first wave of Spanish troops, landing in the heartland of al-Karim's tribe, being the Spanish Foreign Legion's second in command, Colonel Francisco Franco. Pinched between these two fascist dictators in spe, the Republic of the Rif collapsed the following year, ending what has rightly been called "one of the more astonishing bids for self-determination by a people bearing the yoke of colonialism."

Abd al-Karim was exiled to the island of Réunion, Napoleon-style, until 1947 when he settled in Cairo. He continued opposing French rule until his death. In 1949, at the behest of Ho Chi Minh's government, he appealed to North African troops fighting for France in Indochina (Vietnam): "The victory of colonialism, even at the other end of the world, is a defeat for us and a setback to our cause. The victory of liberty in any part of the world is our victory, the sign of our approaching independence."

This history, though all but forgotten, is undisputed. More contentious are the oral traditions in the Rif insisting that the Spanish deployed chemical weapons to quell the Rifi. Old people have described how a 'yellow smoke' burned the skin, causing asphyxiation. Among them is the nearly 100 years old Mohammad Farji, who told Islam Online how "the sky was pouring sulfur-similar liquids, people went blind and frail, cattle perished and vast swathes of farmlands became wastelands." If true, this would be an unacknowledged crime against humanity, since chemical arms were internationally banned through the Treaty of Versailles in 1919; the year Britain used similar methods in Iraq.

In his book Historia Secreta de Annual (Madrid, 1999), Spanish historian Juan Pando confirms the use of German-produced mustard gas in aerial attacks from 1923 on. Gas being the treacherous weapon it is, official records abound with names of poisoned Spaniards. (Presumably, such self-toxication had graver effects than the Rifi attempts at retaliation: throwing bombs filled with chili powder.) And Sebastian Balfour, a British historian, shows in his Deadly Embrace (London, 2002) that Spain deployed chemical weapons as early as 1921 and intensively from 1924, killing thousands. Balfour believes it is high time for Spain to recognize this and offer apologies to the victims, as demanded by Moroccan NGOs.

Locals allege that the chemical weapons, as well as inducing cancer, are still rendering farmland arid.

Some of the latter - notably the local Association for Toxic Gas Victims - go further, asserting that the war crimes still produce fresh victims today. According to the activists, hospital records reveal that 60 percent of Morocco's prevalence of larynx and stomach cancer is found in the affected parts of the Rif. As Pando notes, however, no such long-term harm is seen after the much more intensive gas use in Europe during World War I. Hence, if the Rifi are indeed abnormally prone to cancer, this must have other causes. Regardless, belief in the mustard gas theory holds strong in the region. It has not helped that the Moroccan government repeatedly has banned international conferences to look into the matter.

Half-forgotten conflicts have a way of weaving themselves into current affairs. Interestingly, it is my understanding that the Moroccans arrested for the Madrid Central Station attacks are Berbers from northern Morocco. If so, and given how local grievances are being reinterpreted to fit the narrative of the West attacking Islam, it is not inconceivable that resentment of the Spanish poison gas, and its supposed late effects, was among the motivating factors. Abd al-Karim, who defeated the Spanish invaders under the banner of jihad, is certainly likely to have been an inspiration.

The legacy of imperialism lives on in other ways as well. As Lee Smith has pointed out on Slate in respect to the incomplete decolonization of Morocco: "If the Spanish electorate believed that committing 1,300 troops to Iraq had needlessly exposed it to the jihadists' ire, it ought to reconsider the 6,000 Spanish forces stationed in Ceuta and Melilla."

There is much to ponder for the once proud colonial power.