 Complete the following phrase:  In 1842 the Ottomans built a fortress at Marsat al Zaafran saffron harbour which became known as Qasr al Zaafran saffron castle, and later as Qasr Sert. The fortress was built under sultan Abdülmecid I as part of the restoration of Ottoman control over Tripolitania after the fall of the Karamanli dynasty. It was around this fortification, which was taken over and repaired by the 