Confirming the belief of many Mexicans that the so-called Zapatista National Liberation Army (EZLN) will not surrender without a fight, however, an army colonel and another soldier were killed on Friday and 10 others wounded in what appeared a well-executed guerrilla ambush.
Colonel Hugo Alfredo Monterola, 43, thought to be the senior commander of the army assault forces in the jungle, was riding a light tank in a convoy near the town of Las Margaritas when the rebels launched their ambush. The fact that they were able to pick out and kill the Colonel with such accuracy suggested sophisticated weapons and well-trained snipers. Since an army statement made no mention of rebel casualties, it was assumed the EZLN snipers had escaped into the jungle.
The incident was the only one reported in the first hours of the army assault, in which troops captured the rebels' former main strongholds including their former HQ in the jungle village of Guadalupe Tepeyac. There subcomandante Marcos, the charismatic, pipe-smoking guerrilla chief in black woollen balaclava, used to hold press conferences and greet Mexican left-wing politicians and intellectuals. Now, it seems, Marcos, identified by President Ernesto Zedillo last week as Rafael Sebastian Guillen, a 37-year-old former philosophy professor, appears to have faded deep into the jungle towards the Guatemalan border, along with his men.
More than 40,000 Guatemalan troops were said to be deployed on their side of the border yesterday. Guatemalan officials denied the mobilisation had anything to do with the Mexican army operations, but there was speculation that the Guatemalan government may have made a deal with Mr Zedillo to cut off the EZLN's only escape route.
Local Indians were said to have blocked airstrips with boulders in an attempt to hinder the army operation. Hundreds of peasants fled the formerly rebel-held zone and tension was high, as troops in light tanks, armoured cars, Jeeps and trucks, jittery after the ambush, sped through the zone with lights on and hooters blaring.
The army and heavily armed special agents of the Mexican Prosecutor- General's officeclaimed successes. They detained several people, including two men listed by Mr Zedillo as guerrilla "sub-commanders", and announced the discovery of arms caches around the country in an apparent attempt to show that the EZLN had a nationwide network and hoped to overthrow the government.
One detainee claimed the rebels had 12,000 men in all, though only 2,000 were armed, and that only the leaders had sophisticated weapons.
There was considerable doubt, however, whether the arms caches could be linked to the Zapatistas. "Some of these so-called arsenals are nothing more than your average respectable Mexican cacique (big landowner) would keep in his closet," said one local journalist.
And two men detained in Chiapas on Friday night, Jorge Javier Elorreaga ("alias Vicente", according to Mr Zedillo) and Jorge Santiago, denied any involvement in the EZLN. The fact that they were picked up in civilian clothes in their homes a day after Mr Zedillo named them gave some credence to their denials. Mr Elorreaga, a video producer, said he had met "Marcos" late last year while making a film for a Mexican television channel.
Mr Santiago, 50, is well known locally for running a UN-funded group that defends the rights of Mayan Indians. Both were taken to the Chiapas capital, Tuxtla Gutierrez, for questioning.
The stakes in Mr Zedillo's gamble, switching from conciliation to all- out assault on the Zapatistas, were raised not only by the colonel's death but by information allegedly linking Bishop Samuel Ruiz of San Cristobal de las Casas with the rebels.
An alleged guerrilla leader detained in Mexico City on Friday, Maria Gloria Benavides ("alias Elisa") said at her preliminary hearing that Bishop Ruiz had known of the New Year 1994 insurrection six months in advance and had tried to dissuade the rebels from going ahead with it.
At a packed press conference in his office behind San Cristobal's historic colonial cathedral on Friday night, the bishop made no direct comment on the claims and appealed to Mr Zedillo to return to a negotiated solution or risk "a fratricidal war". Hundreds of people, including local Indians, gathered in an attempt to see the bishop, who, although white, speaks Indian languages and is revered by indigenous peasants as Tatik (father).
In taking the offensive, Mr Zedillo appears to have bowed to the hardline faction of his ruling Institutional Revolutionary Party (PRI). Many Mexicans believe PRI hardliners, fearful of democratic opening and loss of power, were behind last year's assassination of two senior PRI figures, the then presidential candidate Luis Donaldo Colosio and the party chairman, Francisco Jose Ruiz Massieu.