Upon receiving official notice of his new assignment, he began to organize efforts to defend Coro from military expeditions sent by the Junta of Caracas.
In 1812 Frigate Captain Domingo de Monteverde arrived in Venezuela with a small force of marines.
He was assigned to aid an anti-republican uprising in small towns near Coro, but managed to continue pushing deep into republican territory and enlarge his forces with locals dissatisfied with the Republic.
After gaining military strength, Monteverde refused to recognize Miyares's authority and established himself as interim captain general of the reconquered areas, something which was ratified by the Cortes of Cádiz – which served as a parliamentary Regency after Ferdinand VII was deposed – when it temporarily split Venezuela into two captaincies general.
In 1814 Miyares was offered the Captaincy General of Guatemala, but it seems he ever assumed the post since José de Bustamante y Guerra was in office during these years.