The John VII Palaeologus reference article from the English Wikipedia on 24-Jul-2004
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John VII Palaeologus

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John VII (1370-1408), surnamed Palaeologus, Byzantine emperor, grandson of John V, initially ruled for only six months in 1390.

He again ruled from 1399 to 1402 as co-emperor when Manuel II was away seeking aid from the West against the Turks.