Teófilo Marxuach Lieutenant Colonel Teófilo Marxuach , ( July 28 , 1877 – November 8 , 1939 ) , was the person who ordered the first shots fired in World War I on behalf of the United States on an armed German supply ship trying to force its way out of the San Juan Bay . Marxuach ordered hostile shots from a machine gun and a cannon located at the Santa Rosa battery of " El Morro " fort , in what is considered to be the first shots of World War I fired by the regular armed forces of the United States against any ship flying the colors of the Central Powers , forcing the " Odenwald " to stop and to return to port where its supplies were confiscated . Early years . Marxuach ( birth name " Teófilo Marxuach Plumey " ) was born in the town of Arroyo , Puerto Rico when the island was still under Spanish colonial rule . His parents were José María Marxuach , twice Mayor of the City of San Juan and Josefina Plumey Irizarry ( daughter of Juan Bautista Plumey and Petronila Irizarry , among the wealthiest landholders in Lares ) . His family had historically played a prominent role in the island ' s commercial and political affairs . Marxuach and his three siblings Acisclo , Teresa ( mother of Puerto Rican radio pioneer Teófilo Villavicencio ) and Amalia were raised and educated in the capital city of San Juan . He studied military engineering at the Academy of Military Engineering in Guadalajara , Spain from September 1895 to July 1900 and graduated with a degree in civil engineering with a lieutenant ' s commission in the Spanish Army . When he returned to Puerto Rico in 1901 , the island was a United States territory and no longer a Spanish colony . Marxuach resigned his commission in the Spanish army and his Spanish citizenship . He then began to work as a civil engineer in the Department of Public Works . He enrolled in Cornell University and continued his engineering studies from 1902 to 1903 . In 1903 , Marxuach wrote and published " El lenguaje castellano en Puerto Rico " ( The Spanish Language in Puerto Rico ) . In 1906 , he married Carolina Acosta y Acosta ( b . 1887 ) , granddaughter of José Julián Acosta in " La Capilla del Cristo " ( Cristo Chapel ) in Old San Juan . They had three children : Teófilo , Gilberto and Raúl Marxuach Acosta Military career with the United States . Puerto Rico became a U . S . Territory after the 1898 Treaty of Paris which ended the Spanish - American War . The United States appointed a military governor and soon the United States Army established itself in San Juan . The Army Appropriation Bill created by an Act of Congress on March 2 , 1889 authorized the creation of the first body of native troops in Puerto Rico . On June 30 , 1901 , the " Porto Rico Provisional Regiment of Infantry " was organized . On July 1 , 1901 , the United States Senate passed a Bill which would require a strict mental and physical examination for those who wanted to join the Regiment . Under the provisions of an act of Congress approved April 23 , 1904 and of Circular No . 34 , War Department , July 29 , 1904 , the recruitment of native Puerto Rican civilians to be appointed the grade of second lieutenant s for a term of four years was approved with the condition that they pass the required tests . Though many civilians from all walks of life applied for the officers appointment on January 1905 , only seven made it that day and one of those seven was Teófilo Marxuach who had from 1903 to 1905 worked as a civil engineer for the Porto Rico regiment in the Aqueduct of Cayey . On March 3 , 1905 he was commissioned with the rank of Second Lieutenant . An Act of Congress , approved on May 27 , 1908 , reorganized the regiment as part of the " regular " Army . Since the native Puerto Rican officers where Puerto Rican citizens and not citizens of the United States , they were required to undergo a new physical examination to determine their fitness for commissions in the Regular Army and to take an oath of U . S . citizenship with their new officers oath . In June 1908 , Lt . Marxuach and all the others passed . He was assigned to the unit in charge of the Progressive Military Map of Puerto Rico from July 12 , 1908 to December 4 , 1908 , during which time he was promoted to the rank of First Lieutenant . First USA shot of World War I fired . By January 30 , 1908 , the " Porto Rico Regiment of Infantry " was stationed at Camp Las Casas in Santurce . Different units were stationed at other forts throughout the island and Lt . Marxuach was stationed at El Morro Castle , ( then an Army base called Fort Brooke ) at San Juan Bay . The United States tried to remain neutral when World War I broke out in August 1914 . However Washington insisted on its neutral right to send ships without them being attacked by German submarines . The American ships carried food and raw materials to Britain . On March 21 , 1915 , Lt . Marxuach was the officer of the day at El Morro Castle . The " Odenwald " , built in 1903 ( not to be confused with the German World War II war ship which carried the same name ) , was an armed German supply ship which tried to force its way out of the San Juan Bay and deliver supplies to the German submarines waiting in the Atlantic Ocean . Lt . Marxuach gave the order to open fire on the ship from the walls of the fort . Sergeant Encarnacion Correa then manned a machine gun which was located along the wall below " La Fortaleza " , the governor ' s residence and fired warning shots at the ship with little effect . Marxuach then fired a shot from a cannon located at the Santa Rosa battery in the upper platform of El Morro , in what is considered to be the first shot of World War I fired by the regular armed forces of the United States against any ship flying the colors of the Central Powers " , forcing the " Odenwald " to stop and to return to port where its supplies were confiscated . The shots ordered by Lt . Marxuach were the first fired by the United States in World War I . International incident . Marxuach ' s actions became an international incident when the German Government accused the United States Government of the holding the Odenwald illegally against its will without firing the customary warning shot as required by international law . The United States Government responded that the official report of the United States War Department made by the commander of the fortress of El Morro Castle , Lt . Col . Burnham , made it clear that only warning shots were made and that none were aimed at the Odenwald . Eventually , the Odenwald was refitted and renamed " SS Newport " by the U . S . Government and assigned to the U . S . Shipping Board , where it served until 1924 when it was retired . In 1917 the Germans resumed the practice of unrestricted submarine warfare , in part leading to America ' s entry into the war . Service in the Panama Canal Zone . On April 6 , 1917 , the U . S . Congress declared war on Germany and on May 14 , 1917 , the " Porto Rico Regiment " was sent to Panama where Marxuach served at the commanding post at Camp E . S . Otis in defense of the Panama Canal Zone as Captain of Infantry . While serving in Panama he was promoted twice , on June 25 , 1918 he was promoted to Major and on September 10 of the same year he was promoted to the rank of Lieutenant Colonel . The Regiment returned to Puerto Rico on March 1919 and was renamed " The 65th Infantry " by the Reorganization Act of June 4 , 1920 . During his military career , Marxuach served at various posts in Puerto Rico . Later years . Marxuach retired on June 30 , 1922 with the rank of Lt . Colonel . He continued to serve with the Organized Reserves of Puerto Rico until November 4 , 1922 . Upon his retirement , Marxuach worked as a civil engineer for the Department of Interior , in a project known as the " Salto de Comerio " . Marxuach also worked in the Customs building in Old San Juan . Lt . Col . Teófilo Marxuach died in San Juan , Puerto Rico on November 8 , 1939 and was laid to rest with full military honors in Santa Maria Magdalena de Pazziz Cemetery in Old San Juan . He was survived by his widow , Carolina Acosta Marxuach , three children , his brother Acisclo and two sisters Teresa and Amalia . His death not only made news in the local news media of the day but , was also posted under the headlines " Lt . Col . Marxuach , World War Figure " in the November 9 , 1939 edition of The New York Times . At the family ' s request , his body was exhumed and on May 3 , 1957 , and was buried in the Puerto Rico National Cemetery located in Bayamon , Puerto Rico next to his son Colonel Gilberto José Marxuach ( 1910 – 1957 ) known as " The Father of the San Juan Civil Defense " .