BEFORE MARTIAL LAW, 1969-72: a new Maoist movement emerges 1969: Group of younger Huks, led by Jose Maria Sison, form Communist Party of the Philippines (CPP) and its military wing, New People's Army (NPA).
August 1971: Marcos declares state of emergency, suspending some constitutional rights, and detains 98 people after accusing NPA guerrillas of setting off grenades at preelection rally.
July 1972: Government says it intercepts shipments of arms from North Korea headed for NPA. Government immediately launches full-scale attack on NPA in Isabella Province in northern Luzon. PICKING UP THE HUK MANTLE
Continuing peasant grievances and intense nationalism that arose during 1960s give new impetus to communist movement. NPA, which initially used Maoist ''people's war'' strategy and tactics, appeals to peasants, mainly in central Luzon. CPP appeals to newly emerging Philippine business class, which wants a smaller role for Chinese and other foreign businesses. CPP turns militant nationalism into urban demonstrations against Marcos, an advocate of foreign investment. MARTIAL LAW, 1972-81: crackdown brings deceptive calm
September 1972: Defense Ministry accuses NPA of trying to assassinate Defense Minister Juan Ponce Enrile Sept. 22. Many believe attempt was staged by government to justify martial law. The next day, Marcos announces martial-law decree (signed Sept. 21), citing need to suppress ''state of rebellion'' instigated by NPA. In next two months, some 6,100 people (including Aquino) are arrested.
Early 1976: Government captures over a dozen key CPP Central Committee members and advisers of Jose Sison, chairman of CCP.
August 1976: Victor Corpus, training chief of NPA, Bernabe Buscaydno, NPA head, and nine other NPA leders are captured. Marcos says, ''I guess this just about eliminates the New People's Army.''
October 1977: Government says for first time that NPA has joined with Muslim rebels seeking independence in Mindanao.
Nov. 10, 1977: Jose Sison is captured. MOVING THE INSURGENCY UNDERGROUND
Marcos offensive against communists during 1972-76 appears successful: Government captures most of the communist leadership, eliminates front organizations, checks growth of the insurgency, drives it underground in its base areas in Luzon.
But many suspect government of using NPA as excuse for tightening authoritarian grip. Public is angered when Marcos suspends writ of habeas corpus (giving Marcos power to arrest and detain people without trial) and other constitutional rights in 1971, and imposes martial law in 1972.
Militarily, government troops are spread thin by fighting two rebel wars: against Muslim secessionists and against the communists. Most of military is fighting Muslim rebellion, allowing NPA to quietly expand its operations from Luzon to Samar and Mindanao. AFTER MARTIAL LAW, 1981-84: rebellion resurfaces
Jan. 17, 1981: Marcos officially lifts martial law.
October/November 1981: Foreign press reports NPA gains against government (especially in Mindanao), just as government seems to be winning against Muslim rebels.
April 1983: Marcos says three-month antiguerrilla sweep in Mindanao kills 436 communists and 19 NPA leaders and that NPA has stepped up its activities.
Aug. 21, 1983: Aquino is assassinated on his return to Manila from self-exile in US.
Sept. 29, 1983: NPA kills 39 soldiers, wounds 17 in Mindanao, the highest toll in single incident in a decade.
May 14, 1984: During parliamentary elections, 91 people are killed in military-communist clashes. Filipinos essentially ignore CPP calls for election boycott.
June, 1984: Army launches largest offensive ever against NPA rebels in northern and central Luzon. MAKING A COMEBACK
''We didn't look into the NPA problem, and it almost blew up into our faces, '' Maj. Gen. Delfin Castro, head of military's southern command, says in 1981. NPA says it has guerrilla fronts in 50 of the 73 provinces.
Income disparity between those in cities and countryside grows as a result of Marcos's economic policies, which favor urban dwellers. Concurrently, more countryside peasants give support to NPA guerrillas.
In 1982, Marcos sets up ''groupings'' in Mindanao, whereby scattered villages are relocated from outlying areas into militarily supervised settlements to undercut local support for insurgents. Strategy fails and is canceled - partly because of Army abuses against peasants - leaving NPA rebels with even more support from villagers. than before.
By April 1983, NPA changes military tactics. Instead of small groups of three to nine guerrillas using hit-and-run tactics to seize arms from small bands of soldiers, NPA now operates in groups of 200 in some areas. Open, large-scale fighting gives NPA regular supply of weapons. By 1984, Western sources estimate NPA operates in 60 provinces.