Cosme Damián de Churruca y Elorza (Mutriku, 27 September 1761 – Battle of Trafalgar, 21 October 1805) was a Basque Spanish noble, an Admiral of the Royal Spanish Armada, scientist and Mayor of Mutriku, who died at the Battle of Trafalgar while commanding the ship of the line San Juan Nepomuceno.
He received his early years education in the Seminary of Burgos. Then, he entered the School of Bergara.
Once he finished his studies, he joined the Naval Academy of Cadiz in 1776, and got his degree in the Naval Academy of Ferrol in 1778, becoming a naval officer.
In 1781, Cosme Damián de Churruca, as an officer of the Spanish Navy, performed heroically in a siege of Gibraltar.
In 1805, a few months before his death, Churruca married María Dolores Ruiz de Apodaca, niece of Juan Ruiz de Apodaca, in 1797. Doña María was only 19 when Churruca died.
The squadron to which the San Juan was assigned sailed on the 13th of August from the port of Ferrol. General Gravina had given Churruca a place of honour, the head of the vanguard. Churruca completed his mission with the highest merit and upon his arrival to Cadiz, redoubled his efforts in training his recently recruited and inexperienced civilian crew. It was at this time he married Maria de los Dolores Ruiz de Apodaca, daughter of Brigadier don Vicente, and cousin of the duke of Venadito.
With the Spanish and French squadrons reunited in the port of Cadiz, they sailed on a course to Marticina, where they took the fort of Del Diamante and captured a British convoy consisting of 12 vessels; in these moments Villeneuve, the chief of the combined fleet, was informed of the presence of Nelson in the Antillas. Villeneuve now decided he had completed his objective, which was to draw British naval forces to the other shore of the Atlantic, so he decided to sail the combined fleet back to Ferrol. However, in the cape of Finisterre, he bumped into the squadron of Admiral Calder, where a battle ensued. The majority of the French squadron continued to Ferrol, while the remaining ships were left to fend for themselves. Their defeat is attributed to the indecision and poor command of the chief of the combined squadron, Villeneuve, by Napoleon, who upon reading reports of the battle said: “The Spanish have behaved like lions, while their admiral only offered curses.”