Antonio de Ulloa was one of the most important sailors and scientists in Spain. In 1733 he embarked on training at the Royal Company of Midshipmen. One of his main scientific achievements was his participation, together with engineer and scientist Jorge Juan, in the famous French Geodesic Mission: a scientific expedition to Ecuador to determine the true shape of the Earth. His work as a researcher and scientist also led to significant discoveries, such as platinum and its properties, an improved understanding of electricity and artificial magnetism, and the publication of his observation of the total solar eclipse in 1779.
His contribution to science was also reflected in the founding of the Study and Cabinet of Natural History, the first establishment of its kind in Spain, although the project never actually came to fruition. This unfinished project was the precursor to the Royal Cabinet of Natural History, now the National Museum of Natural Sciences. He also created the Astronomical Observatory of Cádiz, and the first metallurgical laboratory in Spain. Besides this, he was a member of the prestigious academies of science in Paris, Berlin, and Stockholm.
The painting is by Sevillian painter José Roldán y Martínez, who was also a teacher and director at Seville's Royal Academy of Fine Arts of Saint Isabel of Hungary. He depicts Ulloa dressed in a lieutenant general's uniform, worn by the Spanish army and navy alike, with a gold-trimmed, blue dress coat, crimson vest, and handkerchief in the 18th-century style. Each element symbolizes the subject's discoveries and accomplishments. In the background are a warship and merchant ship.