During the year-long siege of Rome by the Goths, Bessas commanded the troops at the Porta Praenestina gate and distinguished himself in a number of skirmishes. Nothing is known of his role in the subsequent events until 540, except that it was probably at about this time that he was raised to the rank of "patricius". In early 538, Bessas had protected Belisarius when the general Constantine tried to kill him during a dispute, but by 540, when Belisarius was preparing to enter Ravenna under pretense of accepting the Gothic offer to become Emperor of the West, he clearly felt that Bessas could not be trusted, and sent him, along with other troublemaking generals such as John and Narses, to occupy remote locations in Italy.