Alejandro O ' Reilly Marshal Alejandro , Conde de O ' Reilly ( 1722 , Dublin , Ireland - March 23 , 1794 , Bonete , Spain ) ( English : Alexander , Count de O ' Reilly ) , was an Irish - born military reformer and Inspector - General of Infantry for the Spanish Empire in the second half of the 18th century . O ' Reilly served as the second Spanish governor of colonial Louisiana , being the first Spanish official to actually exercise power in the Louisiana territory after France ceded it to Spain . For his much appreciated services to the Crown of Spain , he was ennobled as a " conde " ( count ) , and granted a coat of arms . Origins and military career . Alexander O ' Reilly was born in Dublin in the Kingdom of Ireland in 1722 . Like many so - called " Wild Geese " of his generation , he left Ireland to serve in foreign , Catholic armies . He joined Spanish forces fighting in Italy against the Austrians . After campaigning in the Spanish invasion of Portugal , he swore allegiance to Spain and rose to become a brigadier general . O´Reilly stayed acting for the Conde de Ricla , twice a Grandee of Spain , in Havana , Cuba , as his adjutant and second - in - command . While in Havana , Ricla and O ' Reilly received the city back from the British forces that had besieged and occupied it at the end of the Seven Years ' War . O ' Reilly analyzed what had gone wrong with the defences of Havana during the successful British siege in 1762 , and recommended sweeping reforms to improve the fortifications , training , practices , and troop organizations , which were quickly approved by the Spanish Crown . With the help of military engineer of the Royal Army , Silvestre de la Abarca , the works of the strategic fortress of La Cabaña was undertaken . In 1765 , King Carlos III sent O ' Reilly to Puerto Rico to assess the state of the defenses of that colony . O ' Reilly , known today as the " father of the Puerto Rican militia , " took a very complete census of the island and recommended numerous reforms , including the instilling of strict military discipline in the local troops . He insisted that the men serving the defence of the realm receive their pay regularly and directly , rather than indirectly from their commanding officers , a long - standing practice that had led to abuses . Some of O ' Reilly ' s recommendations resulted in a massive 20 - year programme of building up the Castle of Old San Juan , now a World Heritage Site . Returning to Cuba , O ' Reilly married into a prominent Cuban family . His wife , Doña Rosa de Las Casas , was the sister of Luis de Las Casas , who served as Governor of Cuba . Today there is a street in Old Havana still named for O ' Reilly , marking the location where this officer came ashore while the English were embarking to leave . O ' Reilly was a cousin of Juan MacKenna , a hero of the Chilean War of Independence . Captain General . O ' Reilly was appointed governor and captain - general of colonial Louisiana while in Spain in April 1769 , with orders to immediately proceed to Havana , embark 3 , 000 troops there , put down the revolt in Louisiana , and re - establish order . Arriving in New Orleans in August 1769 , O ' Reilly took formal possession of Louisiana . O ' Reilly then held trials and severely punished those French Creoles responsible for the expulsion of Spain ' s first Governor Antonio de Ulloa from the colony . He is still remembered in New Orleans as " ' Bloody ' O ' Reilly " because he had six prominent rebel Frenchmen executed in October 1769 . Other French rebels were exiled , and some sent for life imprisonment in the Morro Castle in Havana , also a World Heritage Site . Having crushed the ringleaders who had led the Rebellion of 1768 , the French uprising against Governor Antonio de Ulloa , ( January 12 , 1716 – July 3 , 1795 ) and Spanish rule , O ' Reilly sent most of his troops back to Cuba , and focused his attention on administratively getting Louisiana back on its feet , and stabilizing the food supply . O ' Reilly reformed many French bureaucratic practices in place before Spanish rule . Again , as in his 1765 mission to Puerto Rico , O ' Reilly ' s proclamations and rulings affected many aspects of life in Spanish Louisiana , including the ability of slaves to buy their freedom , and the ability for masters to more easily manumit slaves . He also banned the trade of Native American slaves . He regularized the weights and measurements used in marketplaces , regulated doctors and surgeons , and improved public safety by funding bridge and levee maintenance . The insult to the dignity of the Spanish Crown having been swiftly dealt with , and good public order restored , O ' Reilly assigned the post of governor of Louisiana to the colonel of the Havana Regiment in December 1769 , retaining the post of captain - general for himself . Louisiana was firmly placed as a dependency of the military and political establishment in Cuba . Return to Spain . Back in Spain after October 1770 , O ' Reilly was charged to organize six new regiments to be trained near Cádiz , ready for transportation to the Caribbean should a new war between Spain and Great Britain break out . In 1775 , O ' Reilly was given command of a major Spanish expedition attacking Algiers . Although this North Africa n campaign failed , the high reputation of O ' Reilly was not destroyed , and he continued to serve as captain - general in southern Spain . He died in the city of Cádiz in 1794 , aged 72 , while on his way to take command of an army in the Eastern Pyrenees that had been ordered to oppose invading French revolutionary forces , just after the beheading of Louis XVI during the French Revolutionary Wars . O ' Reilly is buried in the parish church in Bonete in Castile - La Mancha , Spain . A street in Cádiz still bears his name , as does one in Havana , Cuba .