In 1378, in consequence of the intrigues of Venice and Genoa to obtain a predominant position at Constantinople, war broke out between the two Republics—the famous Chioggia war—in which Ragusa too was involved. The Genoese induced Francesco Carrara, lord of Padua, who had been humbled but not subdued by Venice, to join them, and further help was obtained from Louis of Hungary. Ragusa, as vassal of that potentate, joined the coalition. But Venice, undismayed, made all preparations for war, and invested Vettor Pisani with the supreme command at sea. A Venetian victory off Cape Antium was won on May 30, and Pisani took Sebenico and Cattaro by storm; these and other towns on the Adriatic coast which his garrisons occupied were harried and blockaded by Ragusan vessels, who also seized this opportunity to destroy the salt-pans of Cattaro, thus ridding the Republic of a dangerous competitor.[310] The Ragusans were in great fear of an attack by the Venetian fleet, and made desperate efforts to strengthen the defences of the town and of Stagno. They also asked for assistance from Tvrtko, King of Bosnia, who offered them a contingent; but on hearing that he was treating with the Venetians, possibly with a view to a move against Ragusa, they refused it. On October 14, 1378, the Genoese fleet under Fieschi put in at Ragusa,[311] where a Ragusan galley joined it, and the admiral received two bombards and a present of money from the Republic. Armed barques issued forth from the town to scour the Adriatic and obtain news of the movements of the Venetian fleet, which were at once transmitted to the Banus of Dalmatia and Croatia at Zara, while privateers cruised about to plunder the enemy’s merchantmen. Ragusan ships were, in fact, the eyes of the allied fleet.

The Senate sent a squadron out under Stefano Sorgo to capture all Venetian or Cattarine ships found in South Dalmatian waters,[312] while envoys went to Cattaro to stir up the people to rebel against Venice and return to Hungarian allegiance. But the Cattarini, still fearing the Venetians, at first refused. Then a joint Genoese and Ragusan fleet made a demonstration against the town, and the authorities promised to raise the Hungarian standard on a certain date. But they failed to do so, and intrigued instead with the King of Bosnia against Ragusa, plundered Ragusan grain ships, and captured the sentinels guarding the approaches to the city on the Monte Sergio. After the total defeat of the Venetian fleet off Pola in May the Ragusans pursued their operations against Cattaro by land and sea with renewed vigour, and by June 26 the town had once more returned to Hungarian allegiance.[313]

Meanwhile the Genoese had carried the war almost to the very gates of Venice, and were besieging Chioggia. A Ragusan contingent under Matteo Giorgi was of great assistance to them in the siege, owing to Giorgi’s knowledge of the use of artillery,[314] and, according to Razzi, he would have prevented the blockade of the Genoese fleet, which was executed, by closing the harbour with sunken boats, if only his advice had been followed.[315] On the defeat of the Genoese the Ragusan galleys managed to escape, and saved a number of the fugitives whose vessels had been sunk (June 24, 1380). Desultory fighting continued for a few months longer, in which the Ragusan galleys took part, and in 1381 peace was signed at Turin. Although in the end the Genoese had been defeated, Venice was by no means victorious, and had to confirm her renunciation of Dalmatia, much to the satisfaction of Ragusa.

But it seemed as though the little Republic of St. Blaize were destined never to be at peace with her neighbours for long. Hardly was the Chioggia war over when a storm-cloud appeared on the side of Bosnia. Now that the Bosnian king had humbled his neighbours and become the most powerful sovereign of the Southern Slaves he began to assume an unfriendly attitude towards Ragusa. His kingdom possessed a stretch of coast from the Bocche di Cattaro to the mouth of the Četina, but the two best ports of that region—Ragusa and Cattaro—were independent Republics owing allegiance to the King of Hungary, who was by no means likely to be always friendly to a powerful and independent Bosnia. If Tvrtko wished to establish a really strong Servian state he would have to occupy those towns. While still Banus he had granted the freedom of his territories to the Ragusans in a charter dated from Bobovac, February 5, 1375.[316] On April 10, 1379, he came to Žrnovica, very near Ragusa, accompanied by his magnates. The Republic sent out a commission of nobles to greet him, and a new and advantageous commercial treaty was concluded, Ragusa agreeing to pay Tvrtko and his successors 500 ipperperi a year for freedom to trade in Bosnia, and 2000 a year as lord of the Servian lands.[317] But this friendship did not last long, for on July 26, 1379, we find the Republic complaining to Louis of Hungary that the people of Cattaro having offered their city to the King of Bosnia, the latter refused to allow foodstuffs to be imported into Ragusa. Louis defended his faithful vassals, and Tvrtko was forced to desist from his annoyances. When, in 1382, Louis died, he left a widow, Elizabeth, who was Tvrtko’s cousin, and two daughters, Mary and Hedwig. He had declared Mary his successor, and betrothed her to Prince Sigismund, son of the Emperor Charles IV., King of Bohemia; but on his death the Poles, who were united to the Hungarians under the same dynasty, refused to be ruled by Mary, and elected her younger sister Hedwig as their queen instead, and even in Hungary and Croatia a considerable party was opposed to Elizabeth and Mary. Civil war broke out and devastated Hungary, Croatia, Dalmatia, and Slavonia for the next twenty-five years. Of these disturbances Tvrtko determined to take advantage, now favouring Elizabeth and Mary, now Charles of Durazzo, who as an Angevin claimed the throne of Hungary also, and his son Ladislas, always with an eye to his own profit.[318] His first thought was for Ragusa. He knew that he could not capture the town without a large fleet, for Ragusan shipping had revived since 1358, and was now very formidable. But he also knew that its inhabitants lived entirely by trade, and he determined to injure them by establishing a rival trading centre at the entrance of the Bocche, making it the chief port and the commercial capital of Bosnia. He called it Sveti Stjepan (San Stefano), but the name was soon changed to Novi, and then to Erzegnovi (Castelnuovo). In violation of his treaties with Ragusa he opened salt-pans at Castelnuovo, which soon became an important trading station not only for the neighbourhood, but for the whole of Dalmatia and Croatia. The Ragusans complained bitterly, and as they obtained Hungarian support, Tvrtko deemed it prudent to give way for the moment, and he promised to close the salt market.[319] But again in 1383 he re-opened it, and the Republic sent Pietro Gondola and Stefano Luccari to Budapest to complain of this breach of the treaty to Queen Mary. The latter at once issued a decree forbidding the inhabitants of Dalmatia and Croatia to trade at Novi.[320]

Tvrtko, not feeling yet strong enough to attack Ragusa openly, allied himself with the Venetians. The latter sold him a large galley fully armed and equipped, and allowed him to have two others built in Venice, sent Niccolò Baseio to him as admiral, and made him honorary citizen of the Republic.[321] These movements disturbed not only Ragusa, but also the two Hungarian queens, who feared that Tvrtko might avail himself of the discontent in Croatia and Dalmatia to raise further trouble. They therefore sent Nicholas of Gara to his court at Sutieska to try to come to some arrangement. Finally Tvrtko was induced to agree not to disturb Ragusa nor the Hungarian dominions, for which promise he was rewarded with the town of Cattaro.[322] This occupation brought him into conflict with the Balšas of Zedda, but after some fighting peace was restored through Venetian mediation. On April 9, 1387, Tvrtko concluded a treaty with Ragusa, in which he promised to protect the city from all enemies, and the Ragusans granted him the right of asylum should he ever be in need of it. It was added that if he should come to the town for any reason, and Queen Mary, who was then a prisoner in the hands of the rebels, should escape, he should be warned in good time and allowed to leave.

By the following year the King of Bosnia’s power in Croatia and Dalmatia had greatly increased, and he became possessed of such important castles as Clissa, Vrana, Ostrovica, and probably Knin, the key of Croatia.[323] He now tried to get hold of the Dalmatian coast towns, as the whole country was in a turmoil of war and revolution, Ragusa alone remaining quiet and loyal to Queen Mary and her husband Sigismund. Various Dalmatian towns promised to pay allegiance to Tvrtko, including Spalato, which was to raise the Bosnian standard on June 15, 1389. But on that very date the death-knell of the Southern Slaves sounded on the fatal “Field of Crows.”[324]

While Tvrtko was thus consolidating his kingdom at the expense of his neighbours, while Hungary was a prey to civil war, while the various princelings of Servia were eternally fighting among themselves, the Turks were ever marching onward. As early as 1375 Marko Kraljević, the hero of Servian popular poetry, had initiated the disastrous policy of calling in Turkish assistance in a quarrel against another Christian prince. Wishing to reconquer Kastoria and other towns in Southern Macedonia and Albania held by the Musacchi family and their ally George I. Balša, he obtained a Turkish contingent for the enterprise, but was defeated by Balša. In 1376 Tvrtko had allied himself with Knez Lazar, who ruled over the Danubian provinces of Servia (the last remnant of the Servian Empire) against Nicholas Altomanović, and continued to remain on good terms with him after Nicholas’s death. He regarded Knez Lazar’s principality as a buffer State between his own dominions and those of the Turks. After the fall of Niš in 1375, and of Sofia in 1382, he gave Lazar assistance, and in 1387 he sent him a contingent which enabled him to cut to pieces a Turkish army of 20,000 men at Pločnik on the Toplica (Old Servia). But the Sultan Murad I. determined to avenge the defeat, and prepared an expedition against Lazar. The latter, seeing himself in great danger, appealed for help from all his neighbours, but the King of Bosnia alone sent him a force, commanded by Vlatko Hranić. The Servian-Bosnian army, under the leadership of Knez Lazar, with Marko Kraljević as chief lieutenant, had its headquarters at Priština, in the plain of Kossovo—a long plateau surrounded by mountains extending from Verisović to Mitrovica. The Turkish army was commanded by the Sultan Murad in person; the right wing was led by his son Bayazet, and the left by his son Yakub. The fight began early on Wednesday, June 15, 1389, and raged all day. For a long time the fortunes of the battle seemed doubtful, and both sides fought with heroic courage. But at last Bayazet succeeded by a sudden attack in throwing the Servian left wing into confusion. At the same time Vuk Branković, whose name has been handed down to the execration of the whole Servian race as a traitor, abandoned the field of battle with all his division. Then Vlatko Hranić and the Bosnian contingent began to give way, and the main body of the Serbs was driven slowly back. Knez Lazar, after fighting like a lion, was killed in the mêlée; Murad was mortally wounded in his own tent by the Servian chief Miloš Obilić, who pretended to be a traitor and to have information to give him. He was himself cut down instantly, and then Lazar’s head was brought in by attendants to cheer the dying Sultan, who expired soon after.

The Turks did not follow up their victory, and from the first news of the fight which he received Tvrtko thought that the Christians had triumphed, and sent messages to that effect to the foreign Powers. In the churches of Florence Te Deums of victory were sung, and the Republic congratulated the Bosnian king. Even when the true result was known no one realised at the time what a crushing blow had fallen on the Slavonic peoples of the Balkans. The native princes continued to fight among themselves regardless of their impending doom, and Tvrtko, who was the most powerful of them, thought more of occupying Dalmatia and Croatia than of strengthening his southern frontier. His enterprises were fairly prosperous; he succeeded in conquering the whole country from the Velebit mountains to Cattaro, Zara and Ragusa alone remaining true to Sigismund, while the three islands of Brazza, Curzola, and Lesina recognised the suzerainty of the Bosnian king (1390). He died in 1391, leaving Bosnia in such a position as she had never enjoyed before. But her power was not based on a solid foundation, and therefore short-lived. His brother, Stephen Dabiša, who succeeded him, soon lost the greater part of Dalmatia and Croatia.

George II. Stračimirov Balša, who now styled himself “absolute lord of all the Zedda and of the coast,” and had established a brilliant court at Scutari,[325] was equally unconscious of the danger, and thought only of capturing Cattaro. He began by occupying the Krivošije,[326] and blocked all the roads leading into the town. Ragusa at the request of Cattaro acted as mediator, and peace was made, probably on an understanding on the part of the Cattarini that they would pay a tribute to George.[327] Ragusa was beginning to be really alarmed at the progress of the Turks in Albania, and saw the necessity of allying herself with the other Dalmatian townships, “propter oppressionem Turcorum.” In 1390 the Senate had tried in vain to mediate between the King of Bosnia and Hungary, so as to end the war which was desolating the country,[328] and now it made a proposal of this kind to Hungary and Venice. At the same time it granted a subsidy of arms and ammunition to George Balša. But mutual jealousies prevented the idea from being realised,[329] and in 1392 George himself was a prisoner in the hands of the Turks.[330] He was soon ransomed, but he lost Scutari, and his power was seriously shaken.