Raphael‘s Portrait of Leo X with cardinals Giulio de’ Medici (later Pope Clement VII) and Luigi de’ Rossi, his first cousins, (Uffizi gallery, Florence)

The final serious attempt to launch a major crusade to the East occurred on the very eve of the Protestant Reformation. Pope Leo X (1513–21) believed that he had no greater task than to organize the defense of Latin Christendom. Sultan Selim I (“the Grim”) (1512–20) was among the most ruthless and effective rulers of the Ottoman Empire. His name struck fear in the hearts of Christians, for they knew of his plans to conquer Europe. Leo invoked Selim’s name when he wrote to Europe’s leaders begging them to put aside their disputes and make ready to take up the cross of Christ. The new king of France, Francis I (1515–47), expressed youthful, bold, and probably sincere promises to put the resources of his kingdom at the disposal of the crusade. In the interim, he requested and received Leo’s permission to tax the French clergy for the crusade. Overjoyed, the pope wrote to King Henry VIII of England (1491–1547), Maximilian I of the German empire (1486–1519), Charles I of Spain and the Netherlands (1516–56), and Manuel I of Portugal (1495–1521), urging them to join with Francis in this holy enterprise. All the monarchs were enthusiastic about the crusade, but not about Francis. They doubted his sincerity, suggesting that he was interested only in collecting tithes. Maximilian even proposed that Germany, England, and Spain should organize their own crusade, which could then conquer France before heading off to the East.

The urgency for a crusade was ratcheted up in 1517 when, in the space of two years, Selim and his armies conquered Syria and Egypt. The Ottoman Empire was now truly massive, encompassing the entire eastern Mediterranean. Europeans were terrified. All the monarchs reiterated their firm intention to crusade, but all insisted that a truce must first be in place. As Henry VIII told a Venetian ambassador to his court:

No general expedition against the Turks will ever be effected so long as such treachery prevails among the Christian powers that their sole thought is to destroy one another; and I think how I could quit this kingdom when such ill will is borne me by certain persons.

To get the ball rolling, Leo appointed a committee of cardinals to gather data concerning Ottoman movements and to make recommendations for a general crusade. The committee finished its work efficiently and in a timely fashion. It recommended that a universal truce be imposed on Europe that would last until six months after the crusade ended. Because it was clear that the kingdoms would not line up behind one ruler, the committee proposed two great armies, one led by the Holy Roman emperor and one by the king of France. As in the Second Crusade, the two forces would work separately but cooperatively. The army should consist of a minimum of sixty thousand infantry, drawn from Germany, Spain, and Bohemia. In addition, four thousand cavalry would come from Italy and France, and another twelve thousand light cavalry from Spain, Italy, Dalmatia, and Greece. The crusader fleet would be donated by Venice, Genoa, France, Brittany, Portugal, and England and would be under the joint command of the kings of England and Portugal. The land forces should march into Italy and assemble at Ancona and Brindisi, where the fleet would ferry them across to Durazzo. From there, they could follow the ancient Via Egnatia straight to Constantinople. They reckoned the total cost of the expedition at 8 million ducats. A general ecclesiastical tithe could pay part of the sum; the rest would come from the kings and barons, who, after all, had the most to lose if the Turks conquered Europe.

Francis committed himself and his armies fully to the plan and began collecting the new clerical tithes without delay. Maximilian offered a more ambitious counterproposal. He suggested that the crusade be organized along a three-year plan. In the first year, he, Charles of Spain, and Manuel of Portugal would land in North Africa and begin marching east. With naval support from England and France, Maximilian felt certain they could conquer Egypt within the year. Meanwhile, an army of Hungarians, Poles, and other east Europeans would attack the Turks in the Balkans. The second year, Francis and his armies would march to Ancona, as the papal commission suggested, and sail to Durazzo. They would then meet the Hungarian and Polish troops at Novi Pazar and conquer all of Greece. The third year, they would close the trap. The French, Hungarian, and Polish troops would besiege Constantinople by land, and the German, Spanish, and Portuguese would surround it on the sea. When the capital surrendered, they would join into one huge army and push the Turks out of Anatolia and Syria. Thus, in the space of three years Maximilian proposed undoing the Muslim conquests of the past millennium.

In March 1518, Leo proclaimed a five-year truce in Europe. England and Venice ratified it immediately. The pope sent legates to France, Germany, Spain, and England to oversee crusade preparations. A tangible excitement filled the courts of Europe, particularly that of England. Young Henry VIII and his lord chancellor Cardinal Wolsey were dead serious about getting the crusade on its feet. Wolsey realized that for a truce to be taken seriously, it must rest on more than just papal words; it would have to be hammered out among Europe’s most powerful states. He rightly saw that France was the greatest obstacle to such a truce. Without papal assistance, Wolsey negotiated a peace between France and England as a precursor to a universal peace. On October 3, 1518, the French and English were the first to sign Wolsey’s Treaty of London, which proclaimed an eternal peace throughout Christendom. Signatories agreed to attack in unison any other signatory that broke the general peace. The pope was overjoyed. In his ratification of the treaty, he proclaimed, “Be glad and rejoice, O Jerusalem, for now your deliverance can be hoped for!” Within a year, twenty-five princes had signed the peace treaty. In gratitude, Leo granted Cardinal Wolsey full authority over the forming crusade.

It seemed that at last the states of Europe would organize a powerful crusade against the Turks. A summit meeting between Francis I and Henry VIII was scheduled, and all countries were informed that they should send ambassadors to the meeting to coordinate preparations for the expedition. But on January 12, 1519, Emperor Maximilian I died, and the crusade died with him as Europe was plunged into a struggle of imperial succession. Charles I and Francis I wanted the imperial crown, and both promised to lead even greater crusades against the Turks if they got it. The reality was rather different. Whichever monarch won the German throne would hardly be on good terms with the loser, and Europe would again be divided. All of Wolsey’s work was for nothing. Pope Leo watched in horror as this bold new crusade became merely a tool of political rhetoric.

When King Charles I became Emperor Charles V (1519–58), Francis washed his hands of everyone and everything. Within a few years, he had allied France with the Ottoman Empire, an alliance that was to last for centuries. The homeland of the crusades was now in league with the Muslims. Leo continued to promote the crusade to Charles V, but even the pope abandoned it in 1520 when news of Selim’s death arrived in Rome. The new sultan, Suleiman, was known to be a quiet and scholarly man committed to peace. All of Europe breathed a sigh of relief.

Europe was wrong—the new sultan was quiet and scholarly, but not peaceful. Suleiman the Magnificent (1520–66) was the most dangerous foe the West had ever faced. He brought the Ottoman Empire to new heights of prosperity while pursuing an aggressive policy of conquest. In 1521, he captured Belgrade. The next year, he began a massive naval bombardment of the Hospitallers at Rhodes. With their fortresses in ruins, the knights were allowed to leave the island with honor, but it was a bitter defeat for the West. Suleiman decisively defeated Christian armies at the Battle of Mohács in 1526, opening the way for him to besiege Vienna in 1529. The battle was close, but Vienna held out. Had it fallen, all of Germany would have been at the mercy of the Turkish armies.