On the return of the Serbians, their discontent was so great that the kral Lazarus, son of the famous Stephen, collected a large army and made an effort for freedom. But, though his armies succeeded in killing twenty thousand of the enemy, Ali Pasha compelled them again to submit to the Turkish yoke. The brave Serbians soon, however, recovered, and Lazarus succeeded in making alliances with his Christian neighbours which promised success. In 1389, with a large army of his own subjects, of Hungarians, Wallachs, Dalmatians, and Albanians, he once more endeavoured to crush the common enemy. A decisive battle was fought on the Plain of Black Birds or Cossovo-pol, in what is now called Old Serbia.[94] Murad and his son Bajazed were in command. The Christians broke the right wing of the Turks, but the issue of the battle was turned by the daring of Bajazed. Lazarus and his suite were taken prisoners, and the triumph of the enemy was complete. The latest historian of Serbia observes that as the battle on the Maritza in 1371 sealed the fate of the Eastern Bulgarians and of the Serbians in Macedonia, so did this battle of Cossovo-pol in 1389 determine that of the Northern Serbians and the Western Bulgarians.[95] [Sidenote: Assassination of Murad.] During or immediately after the battle, there followed a dramatic incident. A young Serb ran towards the Turkish army, and when they would have stopped him declared that he wanted to see their sultan in order that he might show him how he could profit by the fight. Murad signed to him to come near, and the young fellow did so, drew a dagger which he had hidden, and plunged it into the heart of the sultan. He was at once cut down by the guards.[96] The Serbians, according to Ducas, did not know of the sultan’s death for a considerable time, and did not defend themselves with their usual courage. Lazarus was captured, and was hewn in pieces. CHAPTER VI REIGN OF MANUEL: ENCROACHMENTS OF TURKS; MANUEL VISITS WEST, SULTAN BAJAZED SUMMONED BY TIMOUR; FRIENDLY RELATIONS BETWEEN MANUEL AND MAHOMET THE FIRST; JOHN ASSOCIATED WITH MANUEL. SIEGE OF CONSTANTINOPLE BY MURAD; ITS FAILURE. EFFORTS AT UNION; MISCONCEPTIONS IN WEST REGARDING GREEK CHURCH CONSTANCY OF ATTEMPTS AT UNION; NEGOTIATIONS FOR MEETING OF COUNCIL OF CHURCH. INTERNAL STRUGGLES IN LATIN CHURCH. EMPEROR INVITED BY BOTH PARTIES; ACCEPTS POPE’S INVITATION; MEETING OF COUNCIL AT FERRARA AND FLORENCE; UNION ACCOMPLISHED; JOHN RETURNS TO CAPITAL; DIVISIONS IN GREEK CHURCH.