John, however, found little or no material help. He left Rome in debt, and on his return to Venice, where, on his Romeward journey, he had been received in great state and promised four galleys, he was detained until he paid his debts. The emperor urged his son Andronicus, who had been appointed regent during the absence of his father, to find the means of releasing him. The son declared that as the treasury was empty and the clergy would not help, he was unable to obtain ransom. His younger son, Manuel, contrived, however, to find in Salonica sufficient money for his father’s release.

Both Urban and his successor, Gregory the Eleventh, displayed a great desire to aid the empire to stem the tide of Moslem progress. Gregory in 1371 urged the kings of France and England to join with the Genoese to save the remnant of Christians in the Holy Land from the Saracens. All their efforts were fruitless.

The Turkish invasion had meantime become more serious than the Saracenic conquests, as the invaders had now penetrated by land and sea respectively as far as Albania and Dalmatia. The pope once more urged Louis of Hungary, the successors of the crusading nobles who still held territory in Greece and along a portion of the coast of the Adriatic, the knights of Rhodes, and the king of Sicily to combine in a great movement with John against the common enemy. Once more he caused a new Crusade to be preached and promised indulgences to those who took up the Cross. He begged the Emperor Charles to make peace with Bavaria so that the empire in the West might join the Crusade. On all sides, however, there was a reluctance to enter upon it. In spite of the pope’s influence and promise to arm twelve galleys for despatch against the Turks, John’s ambassador returned from the West having completely failed in obtaining aid.

Gregory the Eleventh was equally persevering in his efforts to bring about the Union of the Churches. Franciscan and Dominican missionaries were sent into the East to expose the wickedness of the schism caused or persisted in by the Orthodox Church. Nuncios were despatched to complete the reconciliation. The emperor was reproached, quite unjustly, because he was unable to persuade or compel his subjects to accept Union and to become reconciled with the Latin priests.

The pontiff, however, did not lose sight of his political object. Louis of Hungary fell under his condemnation because he had neglected to engage in the Crusade. But Louis had seen the great defeat of Bulgaria and Southern Serbia on the Maritza in 1371 and was not prepared to make war hastily against so formidable a foe as the Turk had then shown himself to be.

In 1374 the pope returned to the charge and urged the king of Hungary to be on watch against the incursions of the Turks into the empire until the fleet prepared at the pontiff’s expense should arrive in the Marmora. At the same time he invited John once more to visit Rome in order to discuss measures for the accomplishment of Union.

In 1375 he again urged Louis of Hungary to do his duty as chief of the Crusade. He sent five hundred knights of Rhodes and an equal number of squires to defend the Greeks. He authorised the bishops in Western lands to apply large sums from the Church revenues for the purpose of resisting the enemy of Christendom. His influence fell far short of his desire. The Hungarian king was reported to have misappropriated the money he had been allowed to acquire from the Church, and the great fleet which the Genoese had collected for the purpose of attacking the Turks endeavoured to depose John in favour of his son Andronicus.

Difficulties with Sultan Murad.

John himself was in serious difficulties with the Ottoman sultan, Murad. These two sovereigns were now, indeed, the two great actors on the stage during several years, but the character of Murad dominated over that of the commonplace John. To avoid possible treachery, the Christian emperor, who was not trusted by Murad, was in 1374 compelled with his son Manuel to follow the sultan in a campaign. During his absence he entrusted the government to Andronicus, his eldest son. Thereupon an accident occurred which seems greatly to have impressed contemporaries. Andronicus entered into an arrangement with the son of Murad by which the two swore to be friends and to act together, when one should become emperor and the other sultan. A definite arrangement may well be doubted and possibly all that passed was due to the impulsiveness of boyish friendship without any likelihood of practical result. Murad, however, when he heard of the agreement, blinded his son, insisted that John should treat Andronicus in the same manner, and threatened war if he did not comply. According to Ducas, John blinded not only Andronicus, but also his infant son.[81] Probably the sight of one eye only was destroyed. Andronicus was imprisoned in the Tower of Anemas with his wife and son, and John’s younger son, Manuel, was crowned as co-emperor. Two years afterwards Andronicus escaped to the Genoese in Galata. With their aid he succeeded in entering Constantinople, proclaimed himself emperor, and shut up his father in the same prison in which he had himself been confined. Two years afterwards the prisoner escaped to Scutari, and Andronicus had the sense to avoid civil war by coming to an arrangement with his father by which John was once more placed on the throne with his son Manuel. Andronicus in compensation received certain of the towns on the north side of the shore of the Marmora.

When Andronicus had succeeded in obtaining possession of the city with the aid of the Genoese, almost his first act was to arrest all the Venetians, with whom the Genoese were again at war. With their aid, John endeavoured to take Tenedos from his enemies, but failed. In the following year (1379) the Genoese united themselves with Louis of Hungary and defeated the Venetians at sea. They were still sufficiently influential in 1382 to compel the emperor to make peace with Andronicus.[82] Constantly strengthening themselves, they entered into a treaty in 1387 with the Bulgarian prince of the Dobrutcha.