On 24 February, following the killing by the F.L.N. of a Bab-el-Oued taxi-driver, a pied noir mob trapped a score of Muslim workers in a cul-de-sac and stabbed and beat them to death. Increasingly a kind of apartheid, which had never previously existed, was growing up in the cities as Muslim workers declined to enter the European quarters — and vice versa.

QUESTION: The phrase 'which had never previously existed' suggests pre-war Algiers was less segregated — worth exploring how quickly colonial cities hardened into separation.

Horne, Alistair, A Savage War of Peace- Alge…, loc. 1578