Usurpation of the throne and reign thumb|The Gate of Charisius, through which John VII entered Constantinople on 14 April 1390 thumb|Political map of the eastern Mediterranean in 1389 Despite the agreement of 1381, which explicitly stated that John VII was the legitimate successor, and Manuel having shown some rebellious tendencies himself, Manuel remained John V's favoured heir and represented John VII's main obstacle on the way to the throne. When Manuel was away campaigning in Anatolia in 1390, John VII, twenty years old, seized the moment and proclaimed himself sole emperor, laying siege to Constantinople. According to the contemporary Russian chronicler Ignatius of Smolensk, 1390 had seen a strong current of opinion in John VII's favour. John VII had secured the support of the Ottoman sultan Bayezid I and the Genoese; shortly before the siege (probably in late 1389) he had even travelled to Genoa in person to rally support. As he travelled back to the Byzantine Empire by land, it is possible that John VII passed through Bulgaria, where he might also have sought the assistance of Ivan Sratsimir and Ivan Shishman, Tsars of Bulgaria in Vidin and Tarnovo, respectively.
Usurpation of the throne and reign thumb|The Gate of Charisius through which John VII entered Constantinople on 14 April 1390 thumb|Political map of the eastern Mediterranean in 1389 Despite the agreement of 1381 which explicitly stated that John VII was the legitimate successor and Manuel having shown some rebellious tendencies himself Manuel remained John V's favoured heir and represented John VII's main obstacle on the way to the throne When Manuel was away campaigning in Anatolia in 1390 John VII twenty years old seized the moment and proclaimed himself sole emperor laying siege to Constantinople According to the contemporary Russian chronicler Ignatius of Smolensk 1390 had seen a strong current of opinion in John VII's favour John VII had secured the support of the Ottoman sultan Bayezid I and the Genoese; shortly before the siege (probably in late 1389) he had even travelled to Genoa in person to rally support As he travelled back to the Byzantine Empire by land it is possible that John VII passed through Bulgaria where he might also have sought the assistance of Ivan Sratsimir and Ivan Shishman Tsars of Bulgaria in Vidin and Tarnovo respectively