After the Crusaders entered
Constantinople on 12 April 1204 and began to sack the city, a large body of citizens as well as what remained of the
Varangian Guard gathered together in the church of
Hagia Sophia to elect a new emperor, as
Alexios V had fled the city. Two nominees presented themselves – Constantine Laskaris and Constantine Doukas (probably the son of John Angelos Doukas, and thus a first cousin to
Isaac II Angelos and Alexios III). Both presented their case to be nominated emperor, but the people could not decide between them, as both were young and had proven military skills. Eventually lots were cast and Laskaris was selected by what remained of the army as the next emperor. Laskaris refused to accept the
imperial purple; escorted by the Patriarch of Constantinople,
John X, to the
Milion, he urged the assembled populace to resist the Latin invaders with all their strength. However, the crowd was unwilling to risk their lives in such a one-sided conflict, and so he turned to the Varangians and asked for their support. Though his pleas to honour fell on deaf ears, they agreed to fight for increased wages, Seeing all was lost, he quickly fled the capital with his brother,
Theodore, in the early hours of 13 April 1204 and the brothers, along with a crowd of refugees, sailed to the Asian side of
Bosporus. and Donald Queller have argued that it was in fact Theodore and not Constantine who was in Hagia Sophia that fateful day, and it was Theodore who was nominated and thus succeeded Alexios V. This uncertainty, plus the fact that Constantine remained uncrowned, means that he is not always counted among the Byzantine emperors. ==Career at Nicaea==