The campaign against the Turks
At the beginning of 1462, Vlad the Impaler launched a campaign against the Turks along the Danube river. It was quite risky, the military force of Sultan Mehmed II being by far more powerful than the Wallachian army. However, during the winter of 1462, Vlad the Impaler was very successful and managed to gain many victories. To punish Vlad the Impaler, the Sultan decided to launch a full-scale invasion of Wallachia. Of course, his other goal was to transform this land into a Turkish province and he entered Wallachia with an army three times larger than Vlad the Impaler's. Finding himself without allies, Vlad the Impaler, forced to retreat towards Tirgoviste, burned his own fields and poisoned the wells along the way, so that the Turkish army would find nothing to eat or drink.
When the Sultan, exhausted, finally reached the capital city, he was confronted by a most gruesome sight: thousands of stakes held the remaining carcasses of some 20,000 Turkish captives, a horror scene which was ultimately nicknamed the "Forest of the Impaled." This terror tactic deliberately stage-managed by Vlad the Impaler was definitely successful, the scene had a strong effect on Mehmed's most stout-hearted officers, and the Sultan, tired and hungry, admitted defeat. Nevertheless, following his retreat from Wallachian territory, Mehmed left the next phase of the battle to Vlad the Impaler's younger brother Radu, the Turkish favorite for the Wallachian throne. At the head of a Turkish army and joined by Vlad the Impaler's detractors, Radu pursued his brother to Poenari castle on the Arges river.
The Turks finally succeeded in forcing Vlad the Impaler to flee to Transylvania in 1462. Reportedly, his first wife committed suicide by leaping from the towers of Vlad the Impaler's castle into the waters of the Arges River rather than surrender to the Turks. The river was afterwards known as the "Princess River". Vlad the Impaler escaped across the mountains into Transylvania and appealed to Matthias Corvinus for aid. Instead the King had him arrested and imprisoned in a royal tower near Buda. Vlad the Impaler remained a prisoner for twelve years.