John IV Lascaris was only a boy of 8 years when he was elevated as emperor of the
Nicaean Empire[?] in
1258 on the death of his father
Theodore II Lascaris. He was the last of the Lascaris emperors that had done much to restore the
Byzantine Empire after the disaster of 1204. His regent was Michael Palaeologus, who later made himself co-emperor as
Michael VIII Palaeologus. Upon Michael's conquest of
Constantinople in
1261, John was ordered blinded, thus making him ineligible to serve as emperor, then imprisoned in a castle on the
Sea of Mamora[?]. He is recorded as having acknowledged
Andronicus II as emperor in
1290.