Between 1954 and 1962, the Front de Libération Nationale fought the French army in Algeria with one explicit aim: to end one hundred and thirty-two years of French rule. France did not regard Algeria as a colony at all — it was constitutionally part of France, three full départements like any in the metropole, home to a million European settlers (the pieds-noirs) and nine million Muslim Algerians who were governed but not granted equal citizenship. The war that followed — café bombings, the Battle of Algiers, mass internment in camps, routine torture, and finally a near-civil-war inside France itself — broke the Fourth Republic, brought de Gaulle back to power in 1958, and ended the European mission in North Africa. Roughly half a million died, the great majority of them Algerian.
Algeria was the hardest of the European decolonizations, because the settler population and the constitutional fiction of integration made a British-style negotiated exit impossible: there was, formally, no France to withdraw to. The French army, humiliated by its defeat at Dien Bien Phu in 1954, fought to redeem itself with techniques that included systematic torture, electrified interrogation, forced relocation of two million rural Algerians into camps, and what would later be classed as crimes against humanity. The war reshaped French politics as much as Algerian: it returned de Gaulle, who founded the Fifth Republic and then — to the army's fury — negotiated the independence he had been recalled to prevent. It produced the OAS, a settler terror group that tried repeatedly to assassinate him, and the failed generals' putsch of 1961. And it produced a generation of reckoning — Sartre, Fanon, Camus — over what colonialism does to the colonizer. When independence came in 1962, the pieds-noirs fled almost overnight, about a million in weeks, and tens of thousands of Muslim harkis who had served France were left to be massacred. Algeria emerged independent but hollowed, under a single-party FLN regime; the savage civil war of the 1990s was in part the unfinished business of 1962.
France and Algeria still share a fraught relationship. France did not legally acknowledge that a 'war' had even occurred until 1999; Macron has since conceded the army's systematic use of torture and called colonialism a crime against humanity, while stopping short of formal apology — and the question of reparation and reckoning remains live, periodically freezing diplomacy and visa policy. The large Algerian-origin population in France is among its most politicized demographics. The Algerian War is also the foundational case study in counter-insurgency doctrine — taught at Western military academies as a warning about how to win every battle and lose the war, and how the methods used in the field can lose it at home.