Philippine troops blocked 25,000 demonstrators trying to march to the palace of President Ferdinand E. Marcos, while tens of thousands of Filipinos joined in nationwide demonstrations against his government. Opposition organizers said three people were wounded and 30 others were detained in Manila. One of the largest demonstrations took place on Negros Island to protest the killing of 20 demontrators by government forces. The protests marked the anniversary of Marcos’ declaration of martial law in 1972. He ended martial law in 1981, but opponents assert that he still has dictatorial powers.