The Ottoman Empire. See more details in Chapters 17 and 18 in 'Charles V: Duty and Dynasty - The Emperor and his Changing World'

As Charles was establishing himself as king in Spain and as Holy Roman Emperor, a new ruler came to the throne in Istanbul. He was to challenge Charles’ very right to call himself ‘Emperor’. Suleiman became sultan in 1520 and was to rule for 46 years. Now known in the west as ‘the Magnificent’ and to Turks as ‘the Law-maker’, Suleiman had ambitions in both east and west. He refused to refer to Charles as anything other than the ‘king of Spain’. Charles for his part always wrote about Suleiman and the Ottomans as ‘the Turk(s)’.

The Ottoman Empire had expanded considerably during the 15th and early 16th centuries. Read More +

Originating in north-western Anatolia under Osman I around 1300, by 1450 they had already expanded to establish a firm base in south-eastern Europe, controlling modern day Bulgaria, Greece and parts of Romania and Albania. Byzantium (Constantinople), unaided by the rest of Europe, fell to Sultan Mehmet II in 1453. He quickly added Serbia and the remainder of Romania and Albania. The Ottomans also challenged Venetian power in the eastern and central Mediterranean, taking major bases around the Greek coast, such as Coron (now Koroni) and Modon (Methoni), the ‘eyes of the Republic’. After a peace agreed in 1503 Venice had a major commercial interest in maintaining a peaceful coexistence with the Ottomans1. Under Selim I the Ottoman focus was on expansion to the south and east. During his short reign (1512 – 1520) Syria, Palestine and Egypt were over-run.

Suleiman inherited a powerful empire on the death of his father, and he had ambitions to expand it further. A Venetian ambassador expressing the hope of welcoming Suleiman to his city in the future was told ‘Certainly, but only after I have captured Rome’. Fortunately for the west, Suleiman, like Charles, had other commitments and other challenges to deal with. He spent considerable time in each decade of his reign on campaigns against the Safavid dynasty in Persia (Iran) led by Shah Tahmasp. However, whenever his eastern border was secure, he was in a position to lead troops into Europe to invade Hungary and threaten Austria, while by sea his fleet posed a challenge throughout the Mediterranean. There were many parts of Europe where the people had good reason to be fearful.

The structure of the Ottoman Empire meant that it could be on a war footing much more readily than Charles was ever able to be. (See 16th century Warfare in ‘Charles’ World’) The division of land within the empire was based on the provision of armed horsemen for war. Additionally, in the ‘devsirme’ (blood tax), Christian children from occupied areas, ideally aged over 10 years old, of obvious intelligence, physically sound, though not an orphan or an only child, were removed from their homes. They were converted to Islam and trained either for the army, to become the feared janissaries, or for administrative posts. Although officially slaves (kul), the most talented could rise to the highest positions as military commanders or ministers of the sultan. Suleiman therefore had under his command what was effectively a permanent standing army at least for the summer campaigning season. It was traditional for the sultan to lead his troops on campaign each year and return to the capital, Istanbul, as it was coming to be known, each autumn; the army expected the bonuses and plunder that came from a successful expedition and could be troublesome if idle for too long.2 At sea Suleiman was able to provide increasing numbers of warships and had experienced, ruthless commanders, together with sufficient conscripted or slave man-power for the vessels.

As an absolute ruler the sultan could raise additional funds for campaigns without the need to ask local representative bodies (as Charles had to in his various dominions). By the 16th century the sultan was also the caliph, the religious leader of the Sunni Muslims. Thus Suleiman did not have to deal with a religious hierarchy that could challenge his power, in contrast to the rivalry between emperor and the pope. He had a strong grip on power, and this stability enabled him to pursue policies relatively unchallenged for much of the time. As Erasmus wrote in 1521 ‘The Turk will invade with all his forces, to do battle for the great prize, whether Christian or Turk be monarch of the entire globe, for the world can no longer bear to have two suns in the sky’.

During the 1520s Suleiman captured Belgrade, expelled the Knights of St. John from Rhodes, and in 1526 defeated Charles’ brother-in-law Louis II and sacked Buda, retaining control of the eastern part of Hungary. In 1529 he led a 120,000 strong army through Hungary, reaching the gates of Vienna by late September. Had he captured the city it would have been another major blow against Christian Europe. That Suleiman failed was the result of experienced defence led by Nicholas, Count of Salm, rain soaked roads making it impossible to transport heavy siege artillery, the spread of disease and hunger amongst his troops and the lateness of the season. The problems of supplying a large army meant that military campaigns were usually restricted to the months between April and October. Suleiman withdrew, but had not yet given up his plans to take Vienna.

When Suleiman again led his troops west from Istanbul in the spring of 1532, Charles wrote to his wife’: ‘The Turkish menace has increased so much that I have even considered coming to an agreement with the Lutherans in order to prevent worse disaster’.3 Charles now had an opportunity to lead a great expedition against the sultan and fulfil his role as Holy Roman Emperor and master of the Order of the Golden Fleece, to carry out ‘great deeds’ and win ‘honour and reputation’. He took his duty as leader of Christendom against the Ottoman threat seriously: ‘I have decided that if the Turk comes in person, which he can only do at the head of a great force, I will go forth with all the forces I can find to resist him’4. He assembled an army at Regensburg, with troops summoned from Germany, the Low Countries and Italy, and moved down the Danube with his most experienced commanders.

The Ottoman advance was again slow, delayed this time by a three week long siege of Guns (Koszeg), in western Hungary, before approaching Vienna. By the time Charles arrived in Vienna on 23rd September 1532, his much stated wish for a decisive confrontation was not to be. Suleiman had already withdrawn his forces, deterred by the slow progress, mindful of the failure of the siege of 1529, aware that maintaining his troops in the field much longer was almost impossible. It has been argued that the campaigns of 1532 were in reality ‘a parade of strength’ in which a major set piece battle was unlikely; instead there had been ‘a competition in splendour’.5 Given the cost of putting together, equipping and supplying the vast armies, neither leader was willing to risk all of this and the enormous loss of prestige if they were defeated. There had been no great victory but Charles was able to claim success in defending Christendom and Suleiman was never again to reach so far west by land.

Despite Suleiman’s stated ambition to take Rome he probably knew that it was unrealistic unless Christian Europe collapsed completely as a result of internal divisions. That divisions existed, between emperor and pope, between Charles and Francis, and between Catholic and Protestant, was undeniable. But every time the Ottoman threat grew sufficient support rallied around Charles to withstand it. In addition, the campaigns of 1529 and 1532 showed the logistical limits of the Ottoman armies. With the campaigns starting from Istanbul and all the problems of supplying a large army as it advanced, coupled with the new defensive methods of the time (See 16th century Warfare in ‘Charles’ World’) it is unlikely that the Ottoman forces could have advanced much further despite the fears of Europe’s leaders and citizens.

The threat in the Mediterranean. However that was not the end of the Ottoman threat to Charles’ lands. Many coastal areas in the Mediterranean had suffered from attacks by Muslim corsairs for decades, just as Muslim shipping had been frequently raided by the Knights of St. John (See 16th century Warfare in ‘Charles’ World’). The threat became more severe after Hayrettin Barbarossa became Suleiman’s admiral. Large fleets of galleys could be built rapidly in the shipyards of Galata on the Golden Horn in Istanbul and these regularly attacked coastal settlements to cause chaos, plunder for booty and capture prisoners for use as galley slaves. Although major sea battles were rare, the raids were terrifying for the inhabitants and something that Charles had to be seen to be trying to prevent.

After major Ottoman raids on the western coast of Italy in 1534, Charles organised an expedition to retake Tunis, the North African port that had fallen to Barbarossa and was being used as a base for such attacks. He took personal charge - another chance to carry out ‘great deeds’. Many of his councillors warned him against such a venture, reminding him of the obvious risks, but he was not to be deterred. In the summer of 1535 he successfully recaptured Tunis, but Barbarossa was able to escape and soon restarted his activities. In 1538 he inflicted a significant defeat on the fleet of the Holy League at Preveza (see - the Battle of Preveza in ‘16th century Warfare’).

Late in 1541 Charles led another large force across the Mediterranean, this time to Algiers. Unable to set sail until October, he ignored all warnings about the risk of unfavourable weather conditions so late in the year. This time he came to grief. Storms made the disembarkation of the soldiers impossible on the 21st and 22nd October and so commenced on 23rd. Although the troops rapidly advanced on Algiers, gaining possession of high ground overlooking the city, on the night of 24th-25th a great storm caused a large number of ships to lose their anchorage and many were destroyed on the rocks. It became impossible to land more troops or supplies, leaving most with food for only two days. Battle was joined and although both sides had limited successes and setbacks, eventually Charles agreed with most of his commanders that withdrawal was the only realistic option. Eventually Doria, his admiral, was able to reassemble the remnants of the fleet and the army marched to meet them under constant attack. There were not sufficient vessels to save everyone. Horses were thrown overboard and many men were abandoned. The survivors reached Cartagena on the Spanish coast in early December.

France was also able to take advantage of the power and size of the Ottoman fleet. On a number of occasions Francis I allied with Suleiman. In 1543 having raided settlements in Sicily and southern Italy in June, Barbarossa joined with a French fleet at Marseilles and together they attacked Nice, ruled by Charles’ ally, the Duke of Savoy. The town was taken and plundered, although the citadel held out, before its captors left in September on the advance of a relief force. The Ottoman fleet then wintered in the French port of Toulon. This provided a safe harbour without the need to travel back to Algiers or Istanbul. It must have been seen as a propaganda coup by Suleiman. With over 100 galleys and 30,000 men in the town, the cathedral was converted into a mosque and the faithful were called to prayer. Many throughout Europe were deeply shocked when they later heard of these events, as must have been the inhabitants of Toulon. The alliance was becoming too awkward for Francis’ reputation. Relations between the French and the Ottomans deteriorated to such an extent that the next spring Francis had to pay Barbarossa to leave.

Suleiman, now regarded as one of the great sultans, was to outlive Charles, dying in 1566 on yet another campaign into Hungary. Although Charles had managed to prevent an Ottoman invasion of central Europe, it was not until the battle of Lepanto in 1571 that a fleet under Don John of Austria, Charles’ natural son, removed the threat of further westward expansion by the Ottomans in the Mediterranean. The Ottoman Empire would last as long as that of the Habsburgs. After a long decline through the 18th and 19th centuries both came to an end with defeat in the First World War.


1Crowley R. Empires of the Sea: The Final Battle for the Mediterranean 1521-1580. Faber and Faber, London (2008) p.366   
2ImberC. Ottoman Empire 1300-1600: the structure of power. Palgrave, MacMillan, Basingstoke. (2002) p.43   
3Brandi, K. The Emperor Charles V (transl. C.V.Wedgewood (1939) p.325   
4Charles to Isabella 6 April 1532.   
5Jardine, L Worldly Goods, A new history of the Renaissance. MacMillan, London. (1996) p.383   
6Crowley, R. Empires of the Sea: The Final Battle for the Mediterranean 1521-1580. Faber and Faber, London (2008) p.74