In 1459, Ottoman Sultan Mehmed II sent envoys to Vlad to urge him to pay a delayed tribute of 10,000 ducats and 500 recruits into the Ottoman forces.
Vlad refused, because if he had paid the 'tribute', as the tax was called at the time, it would have meant a public acceptance of Wallachia as part of the Ottoman Empire.
Vlad, just like most of his predecessors and successors, had as a primary goal to keep Wallachia as independent as possible.
Vlad had the Turkish envoys killed on the pretext that they had refused to raise their "hats" to him, by nailing their turbans to their heads.