Template:On this day - March 7

Maria of Aragon

• 321 – The Roman Emperor Constantine declares Sunday ("the venerable day of the Sun") the seventh day of the week, instead of the Jewish Sabbath.
• 1517 – Death of Maria of Aragon, fourth daughter of the Catholic Monarchs, Isabella I of Castile and Ferdinand II of Aragon, Infanta of Castile and of Aragon, and Queen consort of Portugal as the second wife of Manuel I (b. 1482).
• 1541 – In the Captaincy General of Chile, Pedro de Valdivia founds the First Cabildo of Santiago, made up of two alcaldes and six regidores. It was the first Western-type institution that country had.
• 1793 – The French National Convention declares war on Spain for its support of the already executed monarch Louis XVI.
• 1805 – Birth of Juana de Vega, Spanish liberal activist and writer, wife of Francisco Espoz y Mina (d. 1872).
• 1827 – At the Cerro de la Caballada, at the southern tip of the province of Buenos Aires (Argentina), the forces of the Empire of Brazil clash with the garrison of Fuerte del Carmen during the Battle of Carmen de Patagones.
• 1847 – In Mexico, a joint invasion force made up of the Army and the Navy of the United States invades the city and port of Veracruz.
• 1885 – Ramón Leocadio Bonachea, general of the Cuban Mambí Army, is executed by firing squad (b. 1845).
• 1939 – During the Spanish Civil War, the coastal defenses of Cartagena sink the Castillo de Olite, a merchant ship used for transporting troops, causing 1476 deaths, the largest number of fatalities on a single ship in the history of Spain.
• 1966 – On the coast of Almería (Spain), the Minister of Information and Tourism, Manuel Fraga, supposedly bathes at the beach of Palomares to try to calm popular fear of radioactivity from a U.S. H-bomb lost at sea after an air accident.
• 1999 – In El Salvador, Francisco Flores, presidential candidate of the ruling party, ARENA, defeats Facundo Guardado, presidential candidate of the opposition party FMLN, with 52 % of the vote in the presidential elections held that same day.
• 2008 – Death of Antonio Colino, engineer, member of the Royal Academy of Exact, Physical and Natural Sciences (b. 1914).
• 2008 – Death of Luisa Isabel Álvarez de Toledo y Maura, Spanish aristocrat, writer and historian (b. 1936).
• 2019 – In Venezuela, a general blackout originating in the turbines of the Guri reservoir leaves the country without electricity for 4 days.