Bajazet advised Andronicus to establish his position by putting the prisoners to death, but to that depth of inhumanity the rebellious son would not descend. Matters remained in this condition for two years, and then the captives managed to escape. Precisely how they found their way out of the tower is a question upon which authorities differ. According to Phrantzes, it was by some deception practised on their Bulgarian guards. Ducas ascribes the escape to the skill of a certain Angelus, surnamed Diabolus, and known by the soubriquet of Diabol-angelus; but whether the deliverance was effected through the angelic power or the satanic cunning of the man, the historian is unable to decide. Chalcocondylas says that the Imperial captives broke through the walls of their dungeon with an iron tool, furnished by the servant who brought their food. According to Venetian authorities, two ineffectual attempts to save the emperor were made by Carlo Zen, on the condition that the island of Tenedos would be granted to the Republic of Venice, thus rescinding the concession of the island to the Genoese by Andronicus. The first attempt, it is said, failed because the emperor refused to escape without his sons; the second, owing to the detection of the plot to deliver him.[553] Once out of prison, John Palæologus and his son Manuel repaired to the Court of Bajazet, prevailed upon him to espouse their cause, and so compelled Andronicus to surrender the throne.[554] Thus the history of the Tower of Anemas reflects the civil broils, the tyranny, the ecclesiastical dissensions, the political feebleness, and the inability to withstand foreign aggression, which marked the decline and fall of the Byzantine Empire. Footnote 543: Anna Comn., xii. pp. 161, 162. Footnote 544: See Schlumberger, _Un Empereur Byzantin au Dixième Siècle_, chap. ii., for a brilliant account of the conquest of Crete by Nicephoras Phocas in 962; cf. Leo Diaconus, _Historia_, lib. i. et ii. Footnote 545: Anna Comn., xii. pp. 153-161. Footnote 546: _Ibid._, pp. 161-164. Footnote 547: Nicetas Chon., pp. 452-458. Footnote 548: Pachymeres, vol. i. pp. 374-403. Footnote 549: For the account of the mission to Servia, see Pachymeres, vol. i. pp. 350-355. Footnote 550: For the circumstances attending the imprisonment of Veccus, see Pachymeres, vol. i. pp. 374-403. Footnote 551: Pachymeres, vol. ii. p. 270. Footnote 552: Pachymeres, vol. ii. pp. 304, 396, 408, 409, where the prison is styled ταῖς κατὰ τὰς Βλαχέρνας εἱρκταις. Footnote 553: Cantacuzene, i. pp. 171, 172; ii. pp. 329-332, 457. Footnote 554: Langier, _Histoire de la République de Venise_, vol. iv. pp. 251, 253. Footnote 555: The history of the imprisonment of these Imperial personages is found in Phrantzes, pp. 49-57: Ducas, pp. 43-46: Chalcocondylas, pp. 40-46, 51, 60-64.