Wallachia, whose ruler, Vlad the Impeller, was the best known in the west, presented itself in the XV-th century as a unique corner of Europe. Lying between the Carpathian Mountains and the Danube, it was inhabited by Romanians, like the other two neighbor countries, Transylvania and Moldavia. Together they formed a defense wall of Europe against the expansion of the Ottoman Empire towards the center of the continent. Since the end of the XIV-th century, the Romanian Countries had been confronting with the powerful Ottoman Empire. The defense war of the three Romanian Countries against the Ottoman power has been representing a permanence of the medieval Romanian history, which couldn't be ignored by the western historians. We mention here the French medievalist Ferdinand Lot, who emphasized, among other things, the importance of the Romanians' resistance, who, through their sacrifice, encouraged the development of the western civilization. The great battles that saved the European civilization, in the XV-th century, took place at the Lower Danube. These battles gave the respite necessary for the rest of the continent to finish their fulfillment of Renaissance and the Reform. Protected from the great invasions, the western monarchies perfected their technology and firearms, which led to balance between Europe and the Ottoman Empire in the XVI-th century.
Taking place in the central and southeastern political context, dominated by the medieval kingdoms Hungary and Poland, the defense war against the Ottomans led by the Romanian Countries presented the characteristics of the late crusade. Under the aegis of papacy and with the participation of some western noblemen from France, Burgundy, the German States, the western medieval military structure confronted with the sultan's powerful army in the crusades at Nicopole, in 1396 and Varna, 1444.