The future leader of Pampanga was born in Guagua on 28 January 1898, to parents Carlos and Casimira Lagman. At age 7, he was tutored by local school teacher Don Tomas Gamboa, staying under his mentorship for three years. By age 10, he was ready to take up his secondary studies—which he completed in Manila, at San Juan de Letran.
Eligio remained at Letran for his college education, where he earned a Bachelor of Arts diploma. He then proceeded to the premiere law school of the country, Escuela de Derecho de Manila, and finished Law. Upon passing the bar in 1917, Eligio became a practicing attorney and quickly made a name for himself as a legal luminary. One of those who joined his law firm office later was another future Kapampangan politico, Jose B. Lingad.
On 26 February 1921, he married his sweetheart Enriqueta, and the two had 7 children. Eligio’s star continued to rise in the next decade, when he ran for and won a seat as a member of the provincial board (vocal) of Pampanga. He briefly took the reins of the Capitol as Pampanga’s interim governor from June to October of 1931, as the incumbent, Sotero Baluyot, had cut short his gubernatorial term to start his stint as a newly-elected Senator. He then turned over the office to incoming governor, Pablo Angeles David.
In 1935, Eligio set his sights on being the Pampanga first representative under the Commonwealth for the 1st District of Pampanga (Magalang, Angeles, Mabalacat), a position he handily won. As a member of the House, he actively joined different commissions, including the Commission of Impeachment, Agriculture, Commerce & Industry, Communication, Judiciary, Mines, National Companies, Privileges, Provinces & Municipalities and Public Works.
In the critical years of the second World War, Eligio once again, was named as Governor of Pampanga under the Japanese rule, from 1942 to 1944. After the war, he resumed his role as an Assemblyman, helping his kabalens start anew by rebuild their shattered lives through his aggressive reconstruction and livelihood programs. Eligio thus fulfilled his promise to be the voice of his people, guided by his motto that defined his life and leadership: “Isulung ing pamaquitalamitan qñg pisasabian ning labuad” (Advance the discussions of relevant issues of our land”).