Pargalı Ibrahim Pasha was the boyhood friend of Suleiman. Ibrahim was originally a Christian from Parga, (Epirus), and when he was young was educated at the Palace School under the devshirme system. Suleiman made him the royal falconer, then promoted him to first officer of the Royal Bedchamber. Ibrahim Pasha rose to Grand Vizier in 1523 and commander-in-chief of all the armies. Suleiman also conferred upon Ibrahim Pasha the honor of beylerbey of Rumelia, granting Ibrahim authority over all Turkish territories in Europe, as well as command of troops residing within them in times of war. According to a 17th-century chronicler, Ibrahim had asked Suleiman not to promote him to such high positions, fearing for his safety; to which Suleiman replied that under his reign no matter what the circumstance, Ibrahim would never be put to death.
Yet Ibrahim eventually fell from grace with the Sultan. During his thirteen years as Grand Vizier, his rapid rise to power and vast accumulation of wealth had made Ibrahim many enemies among the Sultan's court. Reports had reached the Sultan of Ibrahim's impudence during a campaign against the Persian Safavid empire: in particular his adoption of the title serasker sultan (سرعسكر سلطان) was seen as a grave affront to Suleiman.
Suleiman's suspicion of Ibrahim was worsened by a quarrel between the latter and the finance secretary (defterdar) Iskender Çelebi. The dispute ended in the disgrace of Çelebi on charges of intrigue, with Ibrahim convincing Suleiman to sentence the defterdar to death. Before his death however, Çelebi's last words were to accuse Ibrahim of conspiracy against the Sultan. These dying words convinced Suleiman of Ibrahim's disloyalty, and on 15 March 1536 Ibrahim was executed.
Sultan Suleiman's two wives (Hürrem and Mahidevran) had borne him seven sons, four of whom survived past the 1550s. They were Mustafa, Selim, Bayezid, and Cihangir. Of these, only Mustafa, the eldest, was not Hürrem Sultan's son, but rather Mahidevran Sultan's, and therefore preceded Hürrem's children in the order of succession. Hürrem was aware that should Mustafa become Sultan her own children would be strangled. Yet Mustafa was recognized as the most talented of all the brothers and was supported by Pargalı İbrahim Pasha, who was by this time Suleiman's Grand Vizier. The Austrian ambassador Busbecq would note "Suleiman has among his children a son called Mustafa, marvelously well educated and prudent and of an age to rule, since he is 24 or 25 years old; may God never allow a Barbary of such strength to come near us", going on to talk of Mustafa's "remarkable natural gifts". Hürrem is usually held at least partly responsible for the intrigues in nominating a successor.
Although she was Suleiman's wife, she exercised no official public role. This did not, however, prevent Hürrem from wielding powerful political influence. Since the Empire lacked, until the reign of Ahmed I, any formal means of nominating a successor, successions usually involved the death of competing princes in order to avert civil unrest and rebellions. In attempting to avoid the execution of her sons, Hürrem used her influence to eliminate those who supported Mustafa's accession to the throne.
Thus in power struggles apparently instigated by Hürrem, Suleiman had Ibrahim murdered and replaced with her sympathetic son-in-law, Rüstem Pasha. By 1552, when the campaign against Persia had begun with Rüstem appointed commander-in-chief of the expedition, intrigues against Mustafa began. Rüstem sent one of Suleiman's most trusted men to report that since Suleiman was not at the head of the army, the soldiers thought the time had come to put a younger prince on the throne; at the same time he spread rumors that Mustafa had proved receptive to the idea. Angered by what he came to believe were Mustafa's plans to claim the throne, the following summer upon return from his campaign in Persia, Suleiman summoned him to his tent in the Ereğli valley, stating he would "be able to clear himself of the crimes he was accused of and would have nothing to fear if he came".
Mustafa was confronted with a choice: either he appeared before his father at the risk of being killed; or, if he refused to attend, he would be accused of betrayal. In the end, Mustafa chose to enter his father's tent, confident that the support of the army would protect him. Busbecq, who claims to have received an account from an eyewitness, describes Mustafa's final moments. As Mustafa entered his father's tent, Suleiman's eunuchs attacked Mustafa, with the young prince putting up a brave defence. Suleiman, separated from the struggle only by the linen hangings of the tent, peered through the chamber of his tent and "directed fierce and threatening glances upon the mutes, and by menacing gestures sternly rebuked their hesitation. Thereupon, the mutes in their alarm, redoubling their efforts, hurled Mustafa to the ground and, throwing the bowstring round his neck, strangled him."
Cihangir is said to have died of grief a few months after the news of his half-brother's murder. The two surviving brothers, Selim and Bayezid, were given command in different parts of the empire. Within a few years, however, civil war broke out between the brothers, each supported by his loyal forces. With the aid of his father's army, Selim defeated Bayezid in Konya in 1559, leading the latter to seek refuge with the Safavids along with his four sons. Following diplomatic exchanges, the Sultan demanded from the Safavid Shah that Bayezid be either extradited or executed. In return for large amounts of gold, the Shah allowed a Turkish executioner to strangle Bayezid and his four sons in 1561, clearing the path for Selim's succession to the throne seven years later. On 7 September 1566, Suleiman, who had set out from Constantinople to command an expedition to Hungary, died before an Ottoman victory at the Battle of Szigetvár in Hungary.
At the time of Suleiman's death, the Ottoman Empire was one of the world's foremost powers. Suleiman's conquests had brought under the control of the Empire the major Muslim cities (Mecca, Medina, Jerusalem, Damascus, Cairo, and Baghdad), many Balkan provinces (reaching present day Croatia and Austria), and most of North Africa. His expansion into Europe had given the Ottoman Turks a powerful presence in the European balance of power. Indeed, such was the perceived threat of the Ottoman Empire under the reign of Suleiman that Austria's ambassador Busbecq warned of Europe's imminent conquest: "On [the Turks'] side are the resources of a mighty empire, strength unimpaired, habituation to victory, endurance of toil, unity, discipline, frugality and watchfulness... Can we doubt what the result will be?...When the Turks have settled with Persia, they will fly at our throats supported by the might of the whole East; how unprepared we are I dare not say."
Even thirty years after his death "Sultan Solyman" was quoted by the English playwright William Shakespeare as a military prodigy in The Merchant of Venice (Act 2, Scene 1).
Suleiman's legacy was not, however, merely in the military field. The French traveler Jean de Thévenot a century later bears witness to the "strong agricultural base of the country, the well being of the peasantry, the abundance of staple foods, and the pre-eminence of organization in Suleiman's government". The administrative and legal reforms which earned him the name Law Giver ensured the Empire's survival long after his death, an achievement which "took many generations of decadent heirs to undo".
Through his personal patronage, Suleiman also presided over the Golden Age of the Ottoman Empire, representing the pinnacle of the Ottoman Turks' cultural achievement in the realm of architecture, literature, art, theology and philosophy. Today the skyline of the Bosphorus, and of many cities in modern Turkey and the former Ottoman provinces, are still adorned with the architectural works of Mimar Sinan. One of these, the Süleymaniye Mosque, is the final resting place of Suleiman and Hürrem Sultan: they are buried in separate domed mausoleums attached to the mosque.