Carlos Del Rosario was a brilliant student and won leadership, oratory and declamation awards. He was chosen city councilor of Manila during Boys' and Girls' Week. He wrote for his high school paper and was chosen as delegate to the secondary school press conferences.
At the Lyceum where he obtained his degree in political science, he was vice-president of the student council. After graduation he taught at the Philippine College of Commerce (now Polytechnic University of the Philippines).
Fellow teachers describe Del Rosario, called Caloy or Charlie, as amiable and easy to get along with, diligent and trustworthy. He was an organization man as well as an effective articulator.
Already he was a student activist in the mid-1960s, having imbibed the ideas of nationalists such as Claro M. Recto, Lorenzo Tañada, Jose Laurel, Teodoro Agoncillo and Renato Constantino. He denounced neocolonialism and, particularly, the highly unequal relationship between the Philippines and the United States. There was a need, he said, for another propaganda movement such as that launched by Jose Rizal, Marcelo H. Del Pilar and Graciano Lopez Jaena which started the Philippine Revolution in 1896. He also believed that the Katipunan revolution led by Andres Bonifacio, Emilio Jacinto and others was unfinished and had to be completed.
His staunch nationalism and advocacy of national sovereignty and independence led him to be among the early organizers of the Kabataang Makabayan in 1964. Del Rosario was the militant youth group’s first vice-president; he was also national treasurer and secretary-general.
During the crucial First Quarter Storm of 1970, he was instrumental in organizing the massive demonstrations, conferences and congresses that helped revive and spread the nationalist movement in the Philippines. That same year, he was a key member of the Movement for a Democratic Philippines (MDP) that mobilized a broad front of activist organizations.
Del Rosario disappeared at the height of student agitation and protest actions. He was last seen on the night of March 19, 1971, putting up posters for a forthcoming MDP national congress inside the PCC campus in Lepanto, Manila. He was expected later that evening at an MDP meeting in Quezon City, but he did not show up.
His parents, suspecting that the military may have had something to do with his disappearance, searched for him in the various military camps. They asked for Malacañang's help. They combed through newspapers, and listened attentively to radio and television newscasts, hoping to get some clues about what happened to their missing son.
But they never found him.
Carlos Del Rosario was 27 years old when he disappeared.