Complex sentence: He approaches Mehmed II and asks him not to take the country's boys, and when that fails, he offers himself in place of the boys, but the Sultan refuses, and demands Vlad's son in addition.
Split into simpler sentences: He approaches Mehmed II and asks him not to take the country's boys. When that fails, he offers himself in place of the boys; but the Sultan refuses and demands Vlad's son in addition.