Marine Section of the Navy Flying School in the island municipal Culebra. As the number of Marine Aviators grew so did the desire to separate from Naval Aviation. The Marine Corps Aviation Company in Puerto Rico consisted of 10 officers and 40 enlisted men. The Porto Rico Regiment returned to Puerto Rico in March 1919 and was renamed the 65th Infantry Regiment under the Reorganization Act of June 4, 1920. It is estimated that 18,000 Puerto Ricans from the Porto Rico Regiment served in the war and that 335 were wounded by chemical gas experimentation the United States conducted as part of its active chemical weapons program in Panama. Neither the military nor the War Department of the United States kept statistics in regard to the total number of Puerto Ricans who served in the regular units of the Armed Forces (United States mainland forces). It is known that four Puerto Ricans died in combat, but it is impossible to determine the exact number of Puerto Ricans who served and died in World War I. The need for a Puerto Rican National Guard unit became apparent to Major General Luis R. Esteves, who had served as an instructor of Puerto Rican Officers for the Porto Rico Regiment of Infantry at Camp Las Casas in Puerto Rico. His request was approved by the government and Puerto Rican Legislature. In 1919, the first regiment of the Puerto Rican National Guard was formed, and General Luis R. Esteves became the first official Commandant of the Puerto Rican National Guard. Interwar years Second Nicaraguan Campaign (1926–1933) After World War I, Puerto Ricans fought on foreign shores as members of the United States Marine Corps. Civil war broke out in Nicaragua during the first months of 1926, and upon the request of the Nicaraguan government, 3,000 U.S. Marines were sent ashore to establish a neutral zone for the protection of American citizens. The American intervention was also known as the Banana Wars. In 1926, Captain Pedro del Valle served with the Gendarmerie of Haiti for three years. During that time he also became active in the war against Augusto Sandino in Nicaragua. In 1927, Lieutenant Jaime Sabater, from San Juan, Puerto Rico, graduated from United States Naval Academy. Private Rafel Toro, from Humacao, Puerto Rico, was part of the U.S. Marine Corps occupation force in Nicaragua, serving with the Guardia Nacional de Nicaragua. On July