Michael Doukas Glabas Tarchaneiotes was born c. 1235, and is first mentioned in c. 1260/62, when he was assigned to capture the city of Mesembria on the Black Sea coast from the deposed Bulgarian tsar Mitso Asen (r. 1256–1257).

[1][2] In c. 1263 he defeated a Bulgarian army at Bizye, fortified Brysis, and proceeded to capture the fortresses Skopos, Petra and Skopelos, and the cities of Agathopolis, Sozopolis, Debeltos and Anchialos.

Upon hearing this, Emperor Michael VIII sent Glabas at the head of an army to put the exiled prince Ivan Asen III on the Bulgarian throne.

[1][2][7][8] In 1297/8, Glabas was named as the governor of the western part of the Empire, with Thessalonica as his seat, and sent to deal with the Serbs, who had continued periodically attacking Byzantine holdings in Macedonia and Albania since 1282.

Despite his great military experience and his disposing of a relatively strong army, Glabas was unable to make any headway as the Serbs relied on guerrilla tactics and refused a pitched battle.

[1][2] In 1304, Glabas was dispatched to counter a Bulgarian invasion under Tsar Theodore Svetoslav (r. 1300–1322), which took several forts and cities along the Balkan Mountains and the Black Sea coast.

Glabas had some success: according to a panegyric by the court poet Manuel Philes, he retook Roussokastron and Mesembria, rebuilt Anchialos and forced the Bulgarians to withdraw behind the Balkan Mountains.