Hayreddin Barbarossa in the context of "Dragut"

The Regency of Algiers was an early modern semi-independent Ottoman province and nominal vassal state on the Barbary Coast of North Africa from 1516 to 1830. Founded by the privateer brothers Aruj and Hayreddin Reis (also known as the Barbarossa brothers), the Regency succeeded the Kingdom of Tlemcen as a formidable base that waged maritime holy war (Jihad) on European Christian powers. It was ruled by elected regents under a stratocracy led by Janissaries and corsairs. Despite its pirate reputation in Europe, Algiers maintained long-standing diplomatic ties with European states and was a recognized Mediterranean power.

The Regency emerged in the 16th-century Ottoman–Habsburg wars. As self-proclaimed ghazis gaining popular support and legitimacy from the religious leaders at the expense of hostile local emirs, the Barbarossa brothers and their successors carved a unique corsair state that drew revenue and political power from its naval warfare against Habsburg Spain. In the 17th century, when the wars between Spain and the Ottoman Empire, Kingdom of France, Kingdom of England and Dutch Republic ended, Barbary corsairs started capturing merchant ships and their crews and goods from these states. When the Ottomans could not prevent these attacks, European powers negotiated directly with Algiers and also took military action against it. This policy would emancipate Algiers from the Ottomans.

Aruj Barbarossa (Arabic: عروج بربروس), known as Oruç Reis to the Turks, was an Ottoman corsair who became Sultan of Algiers. The elder brother of the famous Ottoman admiral Hayreddin Barbarossa, he was born on the Ottoman island of Midilli (Lesbos in present-day Greece) and died in battle against the Spanish at Tlemcen.

He became known as Baba Aruj (Father Aruj) when he transported large numbers of Morisco, Muslim and Jewish refugees from Spain to North Africa; in Europe he was known as Barbarossa.

Ottoman Tunisia — also known as the Eyalet of Tunis or the Regency of Tunis — was a semi-autonomous territory of the Ottoman Empire, that existed from the 16th to the 19th century, located roughly in present-day Tunisia (and parts of what is now eastern Algeria.)

The Ottoman presence in the Maghreb began with the conquest of Algiers in 1516 by the Ottoman Turkish corsair, Beylerbey Aruj Barbarossa (Oruç Reis). In 1534, the Ottoman Navy under the command of Kapudan Pasha Hayreddin Barbarossa, Aruj's younger brother, captured Tunis from the Hafsid dynasty. Less than a year later, in 1535, the Holy Roman Emperor, Charles V sent a multinational invasion force to wrest control of Tunis, overwhelming the Ottoman garrison. Following the final Ottoman reconquest of Tunis from Spain in 1574, the Ottomans maintained control of Tunis for over three centuries. Ottoman rule came to an end following the French conquest of Tunisia in 1881.

Ottoman Tunisia — also known as the Eyalet of Tunis or the Regency of Tunis — was a semi-autonomous territory of the Ottoman Empire, that existed from the 16th to the 19th century, located roughly in present-day Tunisia (and parts of what is now eastern Algeria.)

The Ottoman presence in the Maghreb began with the conquest of Algiers in 1516 by the Ottoman Turkish corsair, Beylerbey Aruj Barbarossa (Oruç Reis). In 1534, the Ottoman Navy under the command of Kapudan Pasha Hayreddin Barbarossa, Aruj's younger brother, captured Tunis from the Hafsid dynasty. Less than a year later, in 1535, the Holy Roman Emperor, Charles V sent a multinational invasion force to wrest back control of Tunis, overwhelming the Ottoman garrison. Following the final Ottoman reconquest of Tunis from Spain in 1574, the Ottomans maintained control of Tunis for over three centuries. Ottoman rule came to an end following the French conquest of Tunisia in 1881.

The siege of Castelnuovo was an engagement during the Ottoman-Habsburg struggle for control of the Mediterranean, which took place in July 1539 at the walled town of Castelnuovo, present-day Herceg Novi, Montenegro. Castelnuovo had been conquered by elements of various Spanish tercios the year before during the failed campaign of the Holy League against the Ottoman Empire in Eastern Mediterranean waters. The walled town was besieged by land and sea by a powerful Ottoman army under Hayreddin Barbarossa, who offered an honourable surrender to the defenders. These terms were rejected by the Spanish commanding officer Francisco de Sarmiento and his captains even though they knew that the Holy League's fleet, defeated at the Battle of Preveza, could not relieve them. During the siege, Barbarossa's army suffered heavy losses due to the stubborn resistance of Sarmiento's men. Even the Venetian refused the promised naval link to Castelnuovo with the supplies and reinforcements; after a general troop parliament, the commanding officer Francisco de Sarmiento asked his captains what his answer should be to Barbarossa's offer to surrender. The captains responded: "Que vengan cuando quieran" (Let them come whenever they want). However, Castelnuovo eventually fell into Ottoman hands and almost all the Spanish defenders, including Sarmiento, were killed. The loss of the town ended the Christian attempt to regain control of the Eastern Mediterranean. The courage displayed by the Old Tercio of Naples during this last stand, however, was praised and admired throughout Europe and was the subject of numerous poems and songs.

Reis (Ottoman Turkish: رئيس raʾīs; sometimes spelled rais) was a military rank in the Ottoman Empire, akin to that of a naval captain or (in the Levant) a commodore, which was commonly added to the officer's name as an epithet during the Ottoman Empire. Examples include:

• Piri "Reis"
• Turgut "Reis"
• Uluç Ali "Reis"
• Hizir "Reis"
• Seydi Ali "Reis"
• Oruç "Reis"

The rank Reis Pasha referred to an Admiral, while the Kapudan Pasha (akin to Grand Admiral; literally "Captain Pasha") title referred to the commander-in-chief of the Ottoman Navy fleet.