In 1500 the Spaniards took Bona, and in 1509 the capture of Oran by Cardinal Ximenes, and of the city of Algiers itself, completed the subjection of nearly the entire province. The Spaniards erected fortifications at Algiers, but shortly before the death of King Ferdinand in 1516 the emir of Metidja called to his aid the pirate Horuk Barbarossa. This chief expelled the Spaniards from Algiers, murdered the emir, and made himself ruler of the city and its territory. Soon afterward he conquered Tenez and Tlemcen. The Spaniards defeated him in 1517, and in 1518 put him to death. His brother and successor Khair-ed-Din sought assistance from the sultan Selim I., and acknowledged that prince as his sovereign. Selim appointed him pasha of Algiers, and sent him a body of troops with which he repulsed the Spaniards and made himself master of the country. Charles V. made an attempt to reinstate the Spanish authority, and a powerful expedition of 370 vessels and 30,000 men crossed the Mediterranean in 1541; but a storm and earthquake dispersed the fleet, and cut off all communication between it and the army. The troops made their escape with a loss of 8,000 men, 15 vessels of war, and 140 transports.

From this time forward there were unceasing hostilities between the Barbary powers and the knights of Malta; thence sprang that system of piracy which made the Algerine corsairs so terrible in the Mediterranean. On the other hand, the boundaries of Algeria were constantly extended in the wars with the neighboring tribes. Before the close of the 10th century the pasha of Algeria had advanced westward as far as the frontier of Morocco. Oran, however, remained in the hands of the Spaniards till 1708. Bugia in the east was conquered in 1554, and in the south the territory of Algeria was extended as far as the desert. Several attempts made by the Spaniards to reconquer the western provinces utterly failed. In 1501 an entire Spanish army was annihilated at Mostaganem, the Algerines capturing 12,000 men. The duke of Beaufort in 1003 and subsequent years gained several successes, but they had no permanent results. The English under Blake (1055), the French under Duquesne (1682 and 1683), the Dutch, and other powers, at various times attacked Algiers; and Duquesne twice bombarded it. Thousands of Christian slaves constantly languished in captivity in Algiers; and societies of pious men were formed, whose express object was to ransom the prisoners.

Meanwhile the authority of the Turkish government had been reduced to a name. The janizaries from 1600 elected their deys, and these finally declared their independence of the Porte. The last Turkish pasha was expelled by Dey Ibrahim in 1705; and the janizaries by tumultuous elections appointed new chiefs, whom in their mutinies they often murdered. The janizaries were recruited from the immigrants from Turkey, no native, though the son of a janizary by a woman of the country, being admitted into their ranks. The dey sent occasional presents to Constantinople as a token of his nominal allegiance; but all regular tribute was withdrawn, and the Turks, hampered by their constant struggles with Russia, were too weak to chastise the rebels of a distant province. In 1775 Spain undertook her last great expedition against Algiers. The fleet consisted of 44 war vessels and 340 transports under Admiral Castejon, and the army, which was under the command of Gen. O'Reilly, of 25,000 men. Like all the former expeditions, it was utterly unsuccessful. The weaker Christian powers, like Naples, Denmark, Sweden, and the Hanse towns, submitted to the annual payment of a tribute, which nevertheless did not always protect their vessels.

England remained inactive because the insecurity of the Mediterranean injured the commerce of other powers more than her own. During the French revolution and the empire, the presence of large fleets in the Mediterranean put a check to the piracies. On the renewal of peace, however, the Algerines recommenced their depredations; but now the Americans, who in 1795 had been compelled to follow the example of European nations, and to subsidize the dey for peace, refused the tribute. In June, 1815, Commodore Decatur encountered an Algerine squadron near Cartagena, took a frigate and a brig, and sailed into the bay of Algiers, where he forced the dey to surrender all American prisoners, and to abandon all future claims for tribute. This bold example was followed by the English, who, under Lord Exmouth, bombarded the city in 1816, and reduced it to ashes, compelling the dey to surrender his prisoners. Piracy, however, was not suppressed, and in 1826 the Algerines openly seized Italian vessels in the Mediterranean, and even carried their incursions into the North sea.

Meanwhile a serious quarrel had broken out with France. In 1823 the dwelling of the French consul had been plundered; the Algerine ruler, Hussein Bey, personally insulted the consul and spoke disrespectfully of the French king; and various outrages were committed on French vessels. Algiers was blockaded, and negotiations were opened between France, Mehemet Ali, and the Porte, by which Mehemet Ali, with the assistance of France, undertook to conquer Algiers, and to pay a regular tribute to the sultan. This was broken off, and the government of Charles X. at last sent an expedition against Algiers in June, 1830, consisting of 38,000 men and 4,000 horses, under command of Gen. Bourmont. Algiers capitulated July 4, on condition that private property and the religion of the country should be respected, and that the dey and his Turks should retire. The French took 17 ships of war, 1,500 bronze cannon, and nearly $10,000,000 in specie. They immediately garrisoned Algiers, and established a military regency. Small squadrons sailed to Tunis and Tripoli, and concluded treaties with these states, which put an end to piracy.

Gen. Bourmont was made a marshal, and within a short time captured Bona, Oran, and Bugia. The French intended to surrender Algiers to the sultan, and instructions to that effect were actually on their way to Constantinople when Charles X. was dethroned, and Louis Philippe decided to retain the conquest. Clausel was sent over as general-in-chief in place of Bourmont. As the Turkish soldiers, who had thus far ruled Algeria, were driven out of the country, the Arab and Kabyle tribes soon rose against the new rulers. Each town had to be captured in detail at an immense sacrifice of life. The Marabouts preached a holy war against the Christian conquerors, and the insurgents found an able chief in the young emir Abd-el-Kader. Clausel was replaced by Ber-thezene, and the latter by Lieut. Gen. Savary, duke of Rovigo, in the course of 1831. In carrying on the war against the natives Savary committed the most treacherous acts. The whole Arab tribe El-Uffia, including the old men, women, and children, were massacred in one night on account of a robbery committed by some members of the tribe.