Then he rapidly made his preparations for defence against the attack of Murad which he knew would follow. It is sufficient for our purpose to say that he was successful, and that at the approach of the winter of 1447–8, Murad’s attempt to recapture Kroya entirely failed, and the great sultan withdrew to Adrianople. Meantime the Christians north of the Danube were preparing to make a greater effort than ever to strike at the power of the sultan. The new pope, Nicholas the Fifth, urged the duty of aiding the Hungarians and the Poles as vigorously as his predecessor. But his appeals to other states were of little avail. Hunyadi, notwithstanding the defeat at Varna, was named lieutenant-general of the kingdom almost immediately on his return, and at once set himself to reconstruct an army. In less than four years he possessed the best-disciplined host which Hungary had yet seen. But it was far too small for the purpose on hand. Among its twenty-four thousand men were two thousand German arquebusers and eight thousand Wallachians. With this force Hunyadi crossed the Danube near Turn-severin and invaded Serbia, because its ruler, whose sister was married to the sultan, refused to break the engagement with Murad. When the sultan, who was preparing for another attempt to defeat Iskender Bey and the Albanians, heard that George of Serbia was on the point of being attacked, he at once made all haste to go to his assistance. Hunyadi encamped near Cossovo, on the same Plain of Blackbirds where, in 1389, Murad the First had been assassinated after his victory. The Turkish army, probably numbering a hundred and fifty thousand men,[156] occupied three days in crossing the Sitnitza, a small river which runs through the plain into the Vardar. Hunyadi, for some reason which is not evident, left his entrenchment and crossed the stream, apparently with no other object than of forcing on the fight. Why he should have done so, since he was hourly expecting the arrival of a detachment of Albanians under Iskender Bey, it is impossible to understand. [Sidenote: Second battle of Cossovo-pol, 1448.] The battle commenced on October 18, 1448. The Turks were drawn up in the same order as at Varna, the Janissaries in the centre surrounded by a trench, behind which were ranged the camels, and behind them again a belt of shields or bucklers fixed in the ground. To the right of the Janissaries was the European, and to the left the Asiatic, division of Murad’s army. On the other side, the centre of the Christian army was occupied by the German and Bohemian arquebusers and some of the best troops of Transylvania. The right wing was formed of Hungarians with a few Sicilian auxiliaries, while the Wallachs were on the left.