Zagan Pasha Zaganos Pasha ( ; fl . 1446 – 1462 ( 1469 ? ) ) was an Ottoman military commander , with the titles and ranks of " kapudan pasha " and the highest military rank , grand vizier , during the reign of Sultan Mehmed II " the Conqueror " . Originally a Christian who was conscripted and converted through the Devşirme system , he became a Muslim and rose through the ranks of the janissaries . He became one of the prominent military commanders of Mehmed II and a " lala " – the sultan ' s advisor , mentor , tutor , councillor , protector , all at once . He removed his rival , Halil Pasha , when he was the Grand Vizier amid the fall of Constantinople . He later served as the governor of Thessaly of Macedonia . Life . Origin and early life . Zaganos was conscripted through the Devşirme system and rose through the ranks of the janissaries . He was originally Christian . Sources do not mention his descent . N . Iorga , citing Pusculus , says that he was of Albanian origin . E . Goldberg , R . Kasaba and J . S . Migdal say that he was either Greek or Serb . D . Nicolle , J . F . Haldon and S . R . Turnbull believes that he was of South Slavic or Albanian origin . M . Philippides believes that he was of either Greek or Albanian origin . He became a committed Muslim after conversion . When Mehmed II was exiled in 1446 , Zaganos accompanied him . Second Vizier . Young Mehmed II had after his return and accession ( 18 February 1451 ) confirmed Halil Pasha as his first Vizier ( even though he seems to have disliked him ) , and raised Zaganos Pasha from third to second Vizier . Halil Pasha had been appointed first Vizier in 1439 , after the demotion of Ishak Pasha . Zaganos , who was younger , was jealous of the position of Halil Pasha . Conquest of Constantinople . During the Siege of Constantinople , the bulk of the Ottoman army were encamped south of the Golden Horn . The regular European troops , stretched out along the entire length of the walls , were commanded by Karadja Pasha . The regular troops from Anatolia under Ishak Pasha were stationed south of the Lycus down to the Sea of Marmara . Mehmed himself erected his red - and - gold tent near the " Mesoteichion " , where the guns and the elite regiments , the Janissaries , were positioned . The Bashi - bazouk s were spread out behind the front lines . Other troops under Zaganos were employed north of the Golden Horn . Communication was maintained by a road that had been constructed over the marshy head of the Horn . After the inconclusive frontal offensives , the Ottomans sought to break through the walls by constructing underground tunnels in an effort to mine them from mid - May to 25 May . Many of the sappers were miners of German origin sent from Novo Brdo by the Serbian Despot . They were placed under the command of Zaganos Pasha . However , the Byzantines employed an engineer named Johannes Grant ( who was said to be German but was probably Scottish ) , who had counter - mines dug , allowing Byzantine troops to enter the mines and kill the Turkish workers . The Byzantines intercepted the first Serbian tunnel on the night of 16 May . Subsequent tunneling efforts were interrupted on 21 , 23 , and 25 May , destroying them with Greek fire and vigorous combat . On 23 May , the Byzantines captured and tortured two Turkish officers , who revealed the location of all the Turkish tunnels , which were then destroyed . On 21 May , Mehmed sent an ambassador to Constantinople and offered to lift the siege if they gave him the city . Constantine XI accepted to pay higher tributes to the sultan and recognized the status of all the conquered castles and lands in the hands of the Turks as Ottoman possession . Around this time , Mehmed had a final council with his senior officers . Here he encountered some resistance ; one of his Viziers , the veteran Halil Pasha , who had always disapproved of Mehmed ' s plans to conquer the city , now admonished him to abandon the siege in the face of recent adversity . Halil was overruled by Zaganos , who insisted on an immediate attack . Having been accused of bribery , Halil Pasha was put to death later that year . Mehmed planned to overpower the walls by sheer force , expecting that the weakened Byzantine defense by the prolonged siege would now be worn out before he ran out of troops and started preparations for a final all - out offensive . After the Ottoman occupation of Constantinople , the Sultan ordered Zaganos to set out with his galleys for Galata , to prevent the Byzantine ships from setting sail . The stories of Halil Pasha ' s collaboration with the Byzantines were most likely spread by the faction of Zaganos . Zaganos succeeded Halil Pasha as Grand Vizier . In 1456 , however , Zaganos was made scapegoat after a failed expedition against Hungarian - held Belgrade . Zaganos ' daughter was expelled from the Sultan ' s harem , and the two were expelled to Balıkesir , where he probably had property . In 1459 , Zaganos returned and became kapudan pasha of the fast - growing Ottoman navy , and the next year he was the governor of Thessaly and Macedonia . Personality and appearance . Zaganos was said to be a tall and intelligent man . He has been called the most cruel Ottoman captain of his time , and is known to have been an enemy of Christians . He was in absolute loyalty to Mehmed II , even when he was just a prince , knowing that his prospects depended on his master ' s success . Zaganos was a soldier who believed that the Ottoman Empire must always expand in order to keep the enemies off balance . He was known for his warlike beliefs and played an important role in the Siege of Constantinople . He was one of the prominent Ottoman military commander s of Mehmed II ( Mehmet the Conqueror ) and a " lala " , at once an advisor , mentor , tutor , councilor , and protector , for the sultan . Military achievements . During the final siege of Constantinople , Zagan Pasha ' s troops were the first to reach the towers . Ulubatlı Hasan was the first soldier who reached the tower . During the siege many of the sappers were placed under the command of Zagan Pasha . Mehmet took Zaganos ' advice almost exclusively . Mehmet II honored him for his loyalty and honesty , along with the Sultan ' s two other Viziers , Halil Pasha and Sarica Pasha , by naming the three great towers of Rumeli Hisari after them . The tower to the south is named after Zaganos Pasha . Family . He had a daughter who was in the Sultan ' s harem . Legacy . His , as well as his family ' s , mausoleum is located in his endowment ( 1454 ) , Zagan Pasha Mosque , in Balıkesir .