Through the example of the border dams deployed during the Algerian War and their effectiveness from a military point of view, the author draws lessons for ongoing or future conflicts of a similar nature. He concludes that no matter how effective military measures may be, they are not sufficient to defeat an insurgency. In order to achieve victory, Western military action must be accompanied by comprehensive action and act as a complement to national or international forces. local.

June 1957. The French army deploys 400,000 men to maintain order in Algeria. The rebellion has spread to all three departments. The National Liberation Army (ALN) then has more than 40,000 fighters. Tunisia and Morocco served as its rear base; new recruits, weapons, ammunition and equipment crossed the borders. The population, willingly or not, hides and feeds the guerrillas. The military situation is worrying for France.

In order to break the guerrilla resistance, the decision is taken to cut its external supply chain by hermetically sealing the borders, then to isolate and successively reduce each of the Wilayas to cut the NLA off from the population.

The battle of the borders, or how to cut off the guerrilla from outside support

Victory, for France as for the insurgents, cannot rest on a decisive battle. The NLA knows that it cannot prevail in regular fighting against French forces. On the other hand, it wants to hold a portion of Algerian territory that would be, for international opinion, the embryo of the territory of a new state. For that, it needs men and weapons. Infiltration across the Tunisian border allows the maquis to grow stronger. Every month, thousands of weapons and fighters join the Wilayas. For its part, the French army does not have the capacity to defeat the rebels and permanently occupy the ground. Only an indirect approach can solve this problem. The NLA must be forced to fight on unfavourable ground, depriving it of the benefit of surprise. The border war has begun.

The Morice Line covers the Tunisian border from the shores of the Mediterranean to the Sahara. 600 km of fortifications, 21 regiments established in the depths and one mission: to cut the NLA off from its rear bases. It consists of a 7,000-volt electrified fence lined on both sides with barbed wire networks and patrols. A post every 10 km reinforces the device and has the technical means to detect intrusions when the electric fence is cut. Four regiments of light infantry are positioned in front of the line, six cavalry regiments defend the fortifications and carry out patrols, six regiments raid the rear and five regiments of the general reserve (paratroopers or legionnaires) track down insurgents who have managed to infiltrate. In addition, thirteen engineer battalions, three helicopter detachments and air force units are in support [1]. 1] The objective is simple: to force the rebels to engage in combat in order to break through and destroy them in encirclement operations. The device is not intended to be static. The line serves as a net, but the fighting takes place upstream and especially behind against groups that have succeeded in a breakthrough. The combat is decentralized, left to the responsibility of the regiments. The unit that has detected an intrusion takes it into account and orders the reinforcements entrusted to it.

Spring 1959. After nine months of work, the Morice line is watertight. The flow of external supplies was seriously dammed up and the NLA lost 20,000 men in its attempts to cross.

The "Challe plan" or the destruction of the interior maquis

On 12 December 1958, Aviation General Challe was appointed to the military command of Algeria. Algiers was reconquered by General Massu. The borders are locked. The coast and the large valleys are squared by the French army and its auxiliaries... The "forbidden zones" remain, refuges for the NLA maquis who criss-cross the mountains of the interior. The political situation in France was difficult; military success was needed in the guerrilla warfare in order to be able to approach the current negotiations from a position of strength.

The operations of the "Challe Plan" lasted from February 1959 to April 1961. Their objective was to suffocate the maquis. The "grid" of already pacified regions, too static and manpower-consuming, was lightened. The "forbidden zones", the guerrillas' refuges, were surrounded one after the other. From west to east, each massif is raked. Operations "Strap", "Spark", "Binoculars", "Precious stones" mobilize more than 40,000 soldiers against Wilayas V, IV, III, II and I. The units of the general reserve are heavily solicited. Foot sweeps are combined with heliborne operations. At the end of each operation the reclaimed land is left to the special administrative sections and their harkas while the hunting commandos hunt down the last rebels.

The military potential of the Wilayas is halved. The NLA has lost 26,000 men in this fighting. Entire regions are secured. The NLA's military strength is estimated at 46,000 in 1958, 20,000 in 1960, 16,000 in 1961.

What can we conclude?

• In Algeria, military victories but a political defeat

On 18 March 1962, France left Algeria. The battles are won but the war is lost. The guerrillas are asphyxiated, the NLA is exhausted, but France has lost the political fight. This nameless war cannot therefore be limited to a series of pacification operations, reclaimed valleys, Fellagas figures shot down or stocks of seized weapons.

Military victory in the face of an insurrection cannot be total; no battle is decisive; a final military victory is therefore impossible.

• Analysis of the drivers of the insurgency

The resilience of a guerrilla group does not just depend on the number of insurgents, the sum of its equipment and external support, but on the ideology that fuels its action.

In Algeria, the NLA's "centre of gravity" was not its external support or logistics, but its fierce desire for independence. The will of the people, especially if it was fuelled by a dominant ideology - a desire for independence and socialism yesterday, a desire for independence and socialism today, a desire for independence and socialism tomorrow, a desire for independence and socialism tomorrow.The will of the peoples, especially if it is fuelled by a dominant ideology - a desire for independence and socialism yesterday, a desire for independence, independence, Islamism and hatred of the West today - does not seem to be defeatable militarily, especially by an army perceived as foreign.

• Transposable lessons?

It is tempting to draw a parallel between the insurgency in Algeria and the Afghan guerrilla warfare, freeing ourselves from space and time. If the history of the Algerian war has been written, the history of the operations in Afghanistan is in progress. We can see some similarities: mountainous terrain, rustic combatants, asymmetrical combat, cultural and ideological clashes, and massive Western military involvement. We can try to draw some tactical lessons from the Algerian war: the importance of territorial networking, the major role of heliborne combat to engage mobile reserves, joint and combined forces coordination and actions to cut the enemy off from the population and its rear bases.

Defeating a guerrilla warfare militarily seems, since the second half of the 20th century, ^almost impossible. The will of the people, driven by a rising ideology, gives a power and a capacity to last to insurrections that are not compatible with our Western agendas. Operations based solely on military action aimed at total victory seem doomed to failure. Western military action must therefore be accompanied by global action and act as a complement to national or local forces.

1] Editor's note: Without forgetting the permanent fire support delivered on very short notice by seven artillery groups of 105 and 155 mm distributed along the Morice Line.

Squadron Leader Lapacherie, Saint-Cyrien of the promotion "Commandant Morin" (1994-1997) is officer of the train weapon. He served with the 515th ^{RT, from} 1998 to 2005, as platoon leader, squadron assistant then unit commander. During this period he took part in various external operations (Kosovo, Croatia, Polynesia). From 2005 to 2009 he was head of department at the 526th ^BT . He left this position to become Planning Officer for MINURCAT at the UN Headquarters. After graduating from the CSEM, he attended the CID courses before moving towards a technical certificate (master's degree at HEC) in mid-2011.