However , Michael Asen 's early death in battle against the Ottomans in 1355 put forward the question of succession once more .
The eldest one , Michael Asen , was proclaimed successor to the throne and co-emperor shortly after Ivan Alexander 's accession to the throne .
Michael Asen 's early death in battle against the Ottomans in 1355 put forward the question of succession once more .
The eldest one , Michael Asen , was proclaimed successor to the throne and co-emperor shortly after Ivan Alexander 's accession to the throne .