 Complete the following phrase:  For years, Smederevo Fortress stood as the last defense against Ottoman assaults. During their attack in 1439, it also became the first site in Serbia to see cannon fire. When it fell in 1459, it became the center of a Turkish sanjak. Later, Smederevo was a province of the Habsburg Monarchy, and between 1805 and 1807 it was once again the center of the 