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 the chemical gas experimentation which the United States conducted as part of its active chemical weapons program in Panama, however 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), therefore, even though it is known that four Puerto Ricans died in combat, it is impossible to determine the exact number of Puerto Ricans who served and perished in World War I.