Pablo was born in Fuentesecas (Salamanca) on the 5th of May, 1778, and had enlisted in the navy at the young age of 13, whereupon he was stationed in Ferrol. Whilst an adolescent, he distinguished himself in actions such as the landing at Sardinia and at the siege of Toulon. Thanks to these early merits, he was soon promoted as sergeant, a rank with which he participated in the Battle of Trafalgar on 21st October, 1805, onboard the vessel "San Ildefonso". He was injured and taken prisoner in the French-Spanish defeat before Nelson.
Morillo then passed on to the army and in July, 1808, became appointed as the sub-lieutenant of the Voluntary Regiment of Llerena, with which he fought in the battle of Bailén. General Castaños noted his audacity and gave him command over a guerrilla unit with which he harassed the French in Extremadura and got promoted to the rank of lieutenant.
It is Castaños himself who decided to send him as the representative of the Central Committee in Galicia, together with lieutenant colonel García del Barrio and the Canon Manuel Acuña y Malvar, with instructions to raise the people against the French. He was promoted to Captain to confer importance to his mission.
Morillo arrived in Vigo on the 21st of March, 1809, one week before the Reconquest, where he tried to lead the siege, which he finally managed after many difficulties. Prior to the surrender of the garrison led by Chalot, he was promoted to the rank of Coronel, in order to satisfy the French commander that he was not surrendering to civilians.
In the posterior battle for Ponte Sampaio , he gained fame as one of its most noteworthy leaders, for which he was conferred honours and received the vocative "The Lion of San Paio".
Years later, he joined the many forces that fought the war against the French in Extremadura, Castilla and the Basque Country, where he accumulated even more military merits and outshone as a strategist.
After the defeat of Napoleon, the then General Morillo was sent as a "pacifier" to America where he was to contain the revolts of liberals and independence seekers. He was highly renowned for his military exploits there for which in 1821, he was appointed as General Commander of Castilla and later of Galicia.
Pablo Morillo died in France on 27th July, 1837, after moving to a Spa to cure himself of the fevers that he had contracted during his stay in America. Besides his many decorations, Morillo was also appointed as the Count of Cartagena.