Manuel Tirso[citation needed] Tecson Yan, Sr. (January 24, 1920 – December 4, 2008) was a Cabinet Secretary of the Aquino, Ramos and Estrada administrations, World War II veteran and Chief of Staff of the Armed Forces of the Philippines from 1968 until 1972. He was said to be the last replaced official and obstacle to Ferdinand Marcos, and whose resignation made it possible for the ex-President to declare martial law in 1972.[1] He holds the singular Philippine Government Record of continuous longest serving public Officer from April 1937 to January 2001 or a total 63 years and 9 months spanning twelve Philippine Presidents.