Suleiman tried again in 1532, but the siege of Güns delayed the army and Vienna was never reached. The failure did not end the rivalry. In 1533, Ferdinand I signed the Treaty of Constantinople, acknowledging Ottoman suzerainty, calling Suleiman his father and suzerain, agreeing to annual tribute, and accepting the Ottoman grand vizier as his brother and equal in rank. The language was as important as the money. Suleiman was not merely winning ground; he was forcing Europe to speak in Ottoman terms. By the 1540s he returned to Hungary with fresh purpose, capturing fortresses after Habsburg attacks on Buda and Pest, and then, after preparing in Edirne in November 1542, he set out again in April 1543.

The 1543 campaign was precise and punitive. After a two-week siege, Esztergom fell on 8 August. Within weeks, Siklós, Székesfehérvár and Szeged also came under Ottoman control. Ferdinand and Charles were forced into a humiliating five-year treaty. Ferdinand renounced his claim to the Kingdom of Hungary and agreed to pay a fixed yearly sum for the lands he still held. Charles V was referred to not as Emperor, but as the King of Spain, a wording that allowed Suleiman to style himself the true Caesar. Later, in 1552, Ottoman forces besieged Eger in northern Hungary, but the defenders under István Dobó held the castle and repelled the attack.

Even in the shadow of Europe, Suleiman was fighting Persia. His father had made war with the Safavids a priority, and after the European front was stabilised, the sultan turned east. The trigger was political and religious: Shah Tahmasp killed the Baghdad governor loyal to Suleiman and installed his own man, while the governor of Bitlis defected to the Safavids. In 1533, Suleiman ordered Pargalı Ibrahim Pasha to lead an army into eastern Asia Minor. Ibrahim retook Bitlis and occupied Tabriz without resistance. Suleiman joined him in 1534, pushing on until the Shah avoided battle and harassed the Ottoman army along the harsh interior. In 1535, Suleiman made a grand entrance into Baghdad and restored the tomb of Abu Hanifa to strengthen local support.

He did not abandon the eastern war after that. In 1548 and 1549, he launched a second campaign against Shah Tahmasp, only to meet the same strategy of withdrawal, scorched earth, and winter attrition in the Caucasus. The Ottomans withdrew with temporary gains in Tabriz and the Urmia region, a lasting presence in Van, control of western Azerbaijan, and some forts in Georgia. Then, in 1553, Suleiman set out on his third and final campaign against the Shah. He had initially lost territories in Erzurum to Tahmasp’s son, but he recaptured Erzurum, crossed the Upper Euphrates, and laid waste to parts of Persia. The result was stalemate, and in 1555 the Peace of Amasya fixed the border between the two empires.

The Peace of Amasya divided Armenia and Georgia between Ottomans and Safavids. Western Armenia, western Kurdistan and western Georgia, including western Samtskhe, went to Suleiman, while eastern Armenia, eastern Kurdistan and eastern Georgia, including eastern Samtskhe, remained with the Safavids. The Ottomans gained most of Iraq, including Baghdad, and with it access to the Persian Gulf. The Persians kept Tabriz and their north-western Caucasian territories, including what is now Azerbaijan and Dagestan. It was a hard border, drawn after years of marching, burning, and waiting. It gave the empire a shape that would endure beyond the life of the man who had ordered the campaigns.

At sea, Suleiman’s reach was just as wide. Ottoman ships had been sailing the Indian Ocean since 1518, and admirals such as Hadim Suleiman Pasha, Seydi Ali Reis and Kurtoğlu Hızır Reis visited the Mughal ports of Thatta, Surat and Janjira. The Mughal emperor Akbar the Great exchanged six documents with Suleiman. In 1538, Aden in Yemen was seized to provide a base against Portuguese possessions on the western coast of the Mughal Empire. The Ottomans failed at Diu in September 1538, but returned to fortify Aden with 100 pieces of artillery, and Sulayman Pasha then took much of Yemen, including Sanaa. With the Red Sea secure, Suleiman disputed Portuguese control of trade routes and maintained contact with the Mughal world throughout the sixteenth century.

From 1526 until 1543, Ottoman soldiers also fought alongside the Somali Adal Sultanate under Ahmad ibn Ibrahim al-Ghazi during the conquest of Abyssinia. After the first Ajuran-Portuguese war, the weakened Adal Sultanate was absorbed into the Ottoman domain in 1559, extending Ottoman influence in Somalia and the Horn of Africa. In 1564, Suleiman received an embassy from Aceh on Sumatra, in modern Indonesia, asking for help against the Portuguese. He answered with an Ottoman expedition that brought military support to the Acehnese. Across the ocean, the contest with Portugal was not only about cannon and ships, but about routes, coinage and sovereignty. The Ajuran Sultanate even struck new currency in Ottoman style to declare its independence from Portuguese economic power.

In the Mediterranean and North Africa, Suleiman answered another rival, Charles V. News reached him that Koroni in Morea, in the modern Peloponnese, had been lost to Andrea Doria. The Spanish presence in the eastern Mediterranean threatened Ottoman supremacy, so Suleiman appointed Khair ad Din, known in Europe as Barbarossa, as admiral-in-chief and charged him with rebuilding the fleet. In 1535, Charles V led a Holy League of 26,700 men to victory at Tunis. Together with the war against Venice the next year, this drove Suleiman into alliance with Francis I of France against Charles. Huge Muslim territories in North Africa were annexed, and the Barbary pirates became part of the wider struggle against Spain.

The pattern continued. In 1541, the Spaniards failed in an expedition to Algiers. In 1542, Francis I sought to renew the Franco-Ottoman alliance, and Polin negotiated terms in which the Ottoman Empire would send 60,000 troops against Ferdinand and 150 galleys against Charles, while France would strike Flanders, raid Spain’s coasts with a naval force, and send 40 galleys to aid the Turks in the Levant. Then came Tripoli. In August 1551, Turgut Reis captured it from the Knights of Malta, who had held it since 1530. In 1553, Suleiman appointed Turgut Reis commander of Tripoli, making it the capital of Ottoman Tripolitania and a centre for Mediterranean piracy. A Christian relief force in 1560 failed at Djerba.

The Knights of Malta, re-established in 1530, drew Suleiman’s wrath again in 1565. The Great Siege of Malta began on 18 May and lasted until 8 September. At first, it looked like Rhodes all over again. Most Maltese cities were ruined and half the Knights were killed. Yet a relief force from Spain entered the struggle, and the Ottomans lost 10,000 men. The local Maltese citizenry won the victory. It was one of the few moments in the reign when the great sultan’s naval might met a wall it could not break. Even so, his fleet still dominated the seas from the Mediterranean to the Red Sea and into the Persian Gulf, and no rival could ignore the scale of that power.

For all the marching and fighting, Suleiman also ruled with pen and law. In Ottoman memory he was Kanuni Suleiman, the Lawgiver. The empire’s supreme law was Shari’ah, which the sultan could not alter, but the Kanuns, covering criminal law, land tenure and taxation, depended on his will. He gathered the judgments of the nine sultans before him, removed repetitions, resolved contradictions, and issued a single code without violating Islamic law. Working with the chief judicial official Ebussuud Efendi, he brought together sultanic law and sacred law. The result, the kanun-i Osmani, would last more than three hundred years, and it helped bind a vast and changing empire to a coherent legal frame.

His reforms reached into daily life. He introduced new criminal and police legislation, fixed fines for specific offences, and reduced the number of cases that required death or mutilation. Taxes were levied on animals, mines, trade profits and import-export duties. Higher medreses offered university-level education, and their graduates became imams or teachers. Around the mosques were libraries, baths, soup kitchens, residences and hospitals. In late 1553 or 1554, after advice from his favourite doctor and dentist Moses Hamon, he issued a firman denouncing blood libels against Jews. It was a specific legal act, but it carried a wider message: the empire’s law could be used to protect as well as to punish.

The court itself became a workshop of brilliance. Under Suleiman, hundreds of artistic societies, the Ehl-i Hiref, worked at Topkapı Palace. Apprentices could rise through the ranks and were paid quarterly. The surviving payrolls from 1526 list 40 societies with more than 600 members. Painters, book binders, furriers, jewellers and goldsmiths came from the Islamic world and from newly conquered Europe, mixing Arabic, Turkish and European cultures. Suleiman was a poet in Persian and Turkish under the name Muhibbi, and he wrote verses that became proverbs. When his son Mehmed died in 1543, he composed a chronogram for the year. Later poets such as Fuzûlî and Bâkî flourished under him, and Elias John Wilkinson Gibb said no age in Turkey gave greater encouragement to poetry.

He was not only a patron of art; he was also a maker of image. He is credited with large-scale cultivation of the tulip, and diplomats visiting his court are thought to have carried the flowers back to Europe, where nobles planted them and artisans turned them into rugs and ceramics. In 1532, during rivalry with the Habsburgs, he had a four-tiered crown made by Venetian merchants for 115,000 ducats through Alvise Gritti and with the encouragement of Makbul İbrahim Pasha. The crown echoed the Pope’s three-tiered one and symbolised the four continents known at the time. Around the same years, Pargalı Ibrahim Pasha brought the Three Beauties from Buda to Istanbul, and a library was formed from books taken from Matthias Corvinus’s collection.

The buildings of the reign still stand as arguments in stone. Suleiman sought to turn Constantinople into the centre of Islamic civilisation through bridges, mosques, palaces, charitable foundations and the work of Mimar Sinan, chief court architect from 1538 to 1588. Sinan designed over 300 buildings, perhaps nearly 500, including monuments in Buda and Mecca. Suleiman restored the Dome of the Rock and the Walls of Jerusalem, renovated the Kaaba in Mecca, and built a complex in Damascus. The Şehzade Mosque, built between 1545 and 1548, commemorated his son Mehmed, who died in 1543. Then, from 1550 to 1557, Sinan raised the Süleymaniye complex on a hill in Istanbul, with mosques, madrasas, a hospital, a caravanserai, a hammam, shops and two mausoleums.

The Süleymaniye Mosque became one of the great symbols of Ottoman architecture, with its central dome and surrounding semi-domes bringing the form to full symmetry. The site had to be terraced and held by massive foundations, and the old grounds of the Eski Saray were transformed into a shrine of power. By then, Suleiman had moved his household to Topkapı Palace, which under his reign gained the permanent Imperial Harem and became the administrative and residential heart of the dynasty until the nineteenth century. The palace was not merely a home. It was the machine room of empire, where the lawgiver, poet, conqueror and husband all moved through the same corridors of state.

His private life altered the court as much as his wars altered the map. He had three known consorts, including Mahidevran Hatun, mother of Şehzade Mustafa, and Hürrem Sultan, known in the West as Roxelana, who became his legal wife in 1534 and the first Haseki sultan. She was a Ruthenian captive, perhaps the daughter of an Orthodox priest, captured by Tatars from Crimea and sold in Constantinople. Suleiman broke with tradition by marrying her and keeping her at court, where she became the first Ottoman woman to take part directly in state affairs. She signed documents, attended council meetings, corresponded with rulers such as Sigismund II Augustus, and helped shape the Polish-Ottoman alliance. Her influence helped usher in the Sultanate of Women.

The bond between Suleiman and Hürrem was matched, and then challenged, by the rise of Pargalı Ibrahim Pasha. Originally a Christian from Parga in Epirus, he had been captured in the Ottoman-Venetian War of 1499 to 1503 and given to Suleiman around 1514. He converted to Islam, became royal falconer, then first officer of the Royal Bedchamber, and was later promoted in 1523 to Grand Vizier and commander-in-chief. Suleiman also made him beylerbey of Rumelia, giving him authority over Ottoman Europe. For thirteen years Ibrahim accumulated wealth and enemies. A quarrel with İskender Çelebi deepened the rift, and Ibrahim supported Şehzade Mustafa as heir, against Hürrem’s interests. At last Suleiman ordered him strangled in his sleep.

The question of succession grew more dangerous with every passing year. Suleiman had at least eight sons and two daughters. Mahidevran’s son Mustafa was the eldest surviving prince, while Hürrem bore Selim, Bayezid, Cihangir, Mehmed and others. Until the reign of Ahmed I, the empire had no formal system for naming an heir, so succession often meant the death of rivals. In 1552, while the Persian campaign was under way, Rüstem was appointed commander-in-chief and intrigue against Mustafa began. Rüstem sent word that the soldiers, seeing the sultan absent, favoured a younger prince. Suleiman believed Mustafa meant to seize the throne. In the Ereğli valley, when Mustafa entered his father’s tent, the eunuchs attacked him and the mutes killed him with a bow-string.

The murder broke the family. Cihangir died of grief a few months later. Selim and Bayezid were sent to different commands, but civil war followed. In 1559, with the help of his father’s army, Selim defeated Bayezid at Konya. Bayezid fled to the Safavids with his four sons, and Suleiman demanded their surrender or death. The Shah took gold and handed Bayezid and the boys to a Turkish executioner, who strangled them in 1561. That grim clearing of the field left Selim as the obvious successor. When Suleiman rode out for his final campaign in 1566, after an absence of about thirteen years from Hungary, the line of inheritance was already fixed.

His death at Szigetvár closed a reign that had lasted from 1520 to 1566, the longest of any Ottoman sultan. Under him the empire’s subjects rose to at least 25 million, and its economic, military and political power reached a notable peak. He had expanded into Hungary, Iraq, North Africa, Yemen, Somalia, the Red Sea, the Persian Gulf and the Indian Ocean. He had negotiated with Francis I, opposed Charles V, humbled Ferdinand I, and been feared by Busbecq, the Austrian ambassador, who warned of the Turks’ strength, discipline and habit of victory. Yet the clearest legacy may be the one carved into his own words on the citadel of Bender in 1537: in Baghdad he was shah, in Byzantine realms caesar, in Egypt sultan, and in Mecca and Medina the hutbe was read in his name.