The first contacts of Francis I with the Emperor Soliman date from 1525. The king of France then pushed the sultan to attack Charles V, which he did on land, in Hungary and Germany, keeping his fleet anchored in Constantinople . In 1526, it was the battle of Mohac, in 1529, the seat of Vienna. The city was saved inextremi- ously by a coalition of Catholics and Protestants.

After the peace of Cambrai in 1529, which consecrated the defeat of the French in Italy, when Charles V reached the peak of his power, Francis I again decided the Grand Turk to attack the Germanic empire. What he did again in Hungary and Germany. This decision was not favorable to the King of France, who had signed a treaty with the Protestant League of Smalkade. He worked to stop the action of the Turks on land, hoping instead to get their help at sea in the Mediterranean.

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Meanwhile, in 1527, Barberousse took over the city from Algiers Kabyles, who had chased him, with the help of Tunisians, in 1520. In 1529, he also took the famous Penon d’Argel, who controlled the port entrance. He could henceforth devote himself entirely to the corsair race, which he had never ceased to exercise.
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The first agreements between France and Turkey did not prevent the king of Algiers from attacking the French, at sea and on land. In 1531 he entered the harbor of Toulon and planned to make the siege of the city, which he judged quickly too well defended. The following year, in 1532, he set up his base between the coast of Provence and the islands of Hyères to carry out actions in the canal between Corsica, Sardinia and the continent. Francis I., enraged by this intrusion on his soil, sent a strong garrison to reconquer Porquerolles and build a fortress there.
Barbarossa behaved like a corsair, without caring about the politics of the Sublime Porte, in relation to which he enjoyed a very great independence of action.

However, the year 1533, saw a sudden change of attitude of Barbarossa compared to France. The privateer realized that without the help of this country he might be crushed by the Spanish power. He spontaneously sent an embassy to Marseilles to negotiate with Francois I. Appointed, soon after, capitan-pasha of the Turkish fleet, he renewed his embassy, in July, in Le Puy, this time in the names of the two powers, Turkish and Algerian.

After his takeover of Tunis in August 1534, Barberousse expected a very strong reaction from Charles V, he made the final agreements with France in December 1534, in Châtellerault, before joining Constantinople to take his command . A truce of 3 years was signed between the three countries.

After consolidating its position in the Mediterranean, by this agreement, Soliman went to war against Persia and remained, for two and a half years, absent from his capital.

Charles V. decided, as Barberousse had foreseen, to take Tunis from the Barbaresques. In January 1535, he sent a letter to Francis I, through the Comte de Nassau who commanded the French fleet in the Mediterranean, to suggest that he join his fleet to that of Christians to drive Muslims out of the Western Mediterranean. This embassy could have succeeded if the Emperor had agreed to surrender the Milanese to the King of France, which he refused, thus reinforcing Francis’ fidelity to his agreement with Barbarossa.

While these negotiations were taking place, Francis I. was trying to convince his ally, Barbarossa, to employ the Turkish fleet to recover the territories of the Duke of Savoy and, above all, to seize, for his benefit, the city of Genoa. The King of Algiers had no time to accede to this request, for on the 14th of June, 1535, Charles V. left Cagliari with an armada of 400 vessels, bearing 26,000 infantry and 1,000 horses, with whom he resumed Tunis , inflicting a severe defeat at Barbarossa.

Undaunted, the latter, while believed to be on the run towards Constantinople, was heading for Spain, surprised the island of Menorca, and seized six thousand captives by sacking Port Mahon.

Taking advantage of the mobilization of the imperial troops in Tunis, the French, observing a benevolent neutrality towards Barbarossa, invaded Savoy and Piedmont. The wily Charles V. did not immediately go to war against France, but proposed to his king a joint action against Constantinople, offering the duchy of Milan as the price of the French participation in the affair. Francis I would have been convinced, despite his beautiful promises made to Barbousse, if the emperor had not shown an obvious evil time.The first alliance between France and Turkey was provisionally saved. [B] On the return of Soliman to Constantinople, in February 1536, Francis I. signed the Capitulations, which his preliminary treaties with Barbarossa had prepared. It was a very detailed treaty of non-aggression on sea, very detailed, in which the Barbary corsairs were involved, which opened the trade route with the Orient to Marseille and Provençal ships, more generally. [/ B] The three parties were faithful to this alliance until the death of Barbarossa, in 1546, which was followed shortly by that of Francis I °, in 1547. Barbarossa, who had long been a supporter of the union with France, saw his During his last days, he became an authoritarian old man who was quick to take umbrage. Francis I. took no direct advantage of this alliance, considered ungodly by all the European courts. The presence of the Ottoman fleet, alongside his own, had a more deterrent than really effective role. This was not always the fault of Barbarossa, the king « very Christian » often hesitant to use this Muslim force against his enemies, Christians like him.