Shortly after enlisting as a cadet in the Royal Guard in 1762, González Llamas saw active service during the Spanish invasion of Portugal that year.

[2] During the War of the Pyrenees, as colonel of the Provincial Grenadiers of New Castile, González Llamas served in the Roussillon under General Ricardos, distinguishing himself at the attack, led by Field Marshal Rafael Adorno, on the French camp at Cornella (August 1793).

[2] Promoted to lieutenant general in 1808, later that year the Junta of Valencia and Murcia accused him of not having faced the enemy and relieved him of his command in that region.

The commission appointed to investigate him, which included the Count of Montijo, fully exonerated him, as did the report submitted by JoséCaro in July 1808.

[3] Shortly afterwards, however, on taking up a post in the Gobierno Supremo, he would hand over the command of his troops to Pedro Roca and become directly involved in the setting up the Cortes of Cádiz.