upon the population made a profound impression upon Western Christians. Probably they learned more of the nature of these cruelties, owing to the presence of Italians and the comparative proximity of Salonica to Western Europe, than ever before. But though women were violated, houses pillaged, churches profaned, and seven thousand of the captives sold into slavery, Europe did not yet understand that these were the ordinary incidents of Turkish conquest. Upon the capture of the city, in 1430, Murad and the Venetians made peace.[133] Great efforts, however, were yet to be made to check the progress of Murad, and if in the course of his triumphal progress to Ephesus he was under the illusion that the European nations were content to allow Moslem invasion to remain unchecked, he was soon undeceived. Hungary, Serbia, and Poland now formed the great line of defence against a Turkish advance, and when, in 1428, the first two states were invaded by the Turks, it became evident to the West that Catholic as well as Orthodox nations would have to resist the progress of Turkish arms. Before the nations attacked were ready, Murad struck swiftly and heavily, and Sigismund, king of Hungary, not having received the aid he expected from Ladislaus, king of Poland, suffered a serious disaster on the Danube. [Sidenote: Preparations to resist Murad.] On receiving news of the Turkish advance, the pope once more preached a new Crusade and called upon all Christians to go to the aid of the Poles and Hungarians. But messengers travelled slowly, and preparations were long. Four years afterwards, in 1433, Murad again invaded Hungary, but was stoutly resisted by Elizabeth, mother of the infant Ladislaus, and had to retire. In withdrawing he attempted to annex Serbia, on the pretext that Bajazed having married the sister of Stephen, the former sovereign, the crown belonged to him as the heir of Ilderim. In 1435, he laid siege to Belgrade, and put out the eyes of two sons of the kral, under the pretext that they had attempted to escape to their father. The siege lasted six months, but the attempt failed. The Serbians defended the city bravely. The Turkish army suffered from malarial fever, and a relieving army under a Polish general compelled them to raise the siege. It is worthy of note that during the absence of the emperor at Ferrara and Florence in order to treat of the Union of the Churches--an absence from his capital of two years and two months (November 1437 to February 1440)--Murad proposed to attack the city and was advised to do so by all his council with the exception of Halil pasha,[134] who pointed out that as John had gone to confer with the representatives of the Christian powers on questions of religion, at the request of the pope, they would feel bound to come to his aid, if advantage were taken of his absence to attack the capital. Halil’s advice was taken.[135] [Sidenote: Hunyadi leader of Christian armies.]