In contrast with China's formidable build up, the Indian Army was struggling to send to the border an inadequate formation of 2,400 soldiers -- the ill-fated 7 Infantry Brigade -- which was short of soldiers, arms, equipment and acclimatisation for high-altitude combat.
Ajai Shukla looks back at the 1962 War.
IMAGE: V K Krishna Menon, then India's defence minister who was blamed for India's ill preparedness during the 1962 War, meets with senior army officers
On October 20, 1962, when China attacked Indian posts on the Namka Chu rivulet near Tawang, marking the start of the disastrous Sino-Indian war, the troops that conducted that attack -- the People's Liberation Army's 11 Infantry Division -- prepared for it in three years of battling Tibetan guerrillas, called the Chushi Gangdruk.
Earlier, on August 25, 1959, the first-ever armed clash between Chinese and Indian soldiers took place, when an Indian patrol ran into a Chinese company (roughly 100 soldiers) stationed in Migyitun -- for work with the masses -- as Beijing euphemistically termed operations against the Chushi Gangdruk.
PLA General Yin Fatang reveals that, on June 11, 1962, the Tibet Military Command constituted the 'Advance Command Post for China-India Border Self-Defence Counter-attack 'code-named Z419 (Z stands for Xizang, or Tibet). Yin was appointed its political commissar.
Four days earlier, PLA General Tan Guansan, who had brutally put down the Lhasa revolt in March 1959, relayed orders from the Chinese Communist party's central committee and central military commission to prepare to fight the Indian Army.
These are from a range of new details of the 1962 Sino-Indian war gleaned by Chinese scholar Jianglin Li, from Chinese Communist party documents and interviews with People's Liberation Army veterans.
Li's research is posted on the War on Tibet Web site in a research article entitled 'Suppressing Rebellion in Tibet' and the China-India Border War.
The war clouds began gathering in May 1962 when Beijing decided to 'create conditions for peacefully resolving the border dispute' by 'resolutely fighting back' against the advancing Indian Army, says Wei Ke, director of Z419's political department.
Then itself, it was decided that the main front would be the eastern sector, specifically the Tawang and Walong areas.
By October, 10,300 Chinese soldiers were placed under Z419 command post, charged with attacking India in Kejielang (the Nyamjang Chu valley) and Tawang, according to a PLA 'Studies on Battle Examples'.
Yin says: 'From mid-June 1962, Z419 command post started to collect intelligence in the battle zone and work on a battle plan.
Intensive military training began, including individual training, unit training and battle exercises at regimental level. Based on the experience of fighting the Chushi Gangdruk, Z419 replaced physically unfit officers and soldiers.
Well-trained rocket launcher operators were dispatched to Tibet from Wuhan, and artillery personnel were sent from several military commands.
Beijing military command sent communications equipment and operators. Over one hundred English, Hindi and Tibetan interpreters from different areas were sent to Tibet for the coming 'self-defence counter-attack'.
Meanwhile, in contrast with China's formidable build up, the Indian Army was struggling to send to the border an inadequate formation of 2,400 soldiers -- the ill-fated 7 Infantry Brigade -- which was short of soldiers, arms, equipment and acclimatisation for high-altitude combat.
Beijing took the final decision to go to war in two meetings.
The first was on October 8, between Mao Zedong and China's top leadership -- Zhou Enlai, Deng Xiaoping, Liu Shaoqi, Zhu De, He Long, Nie Rongzheng and Luo Ruiqing.
The next day, Z419 received the pre-order for battle.
The die was cast, according to General Zhang Guohua, who was selected to command the battle; he flew back to Lhasa from Beijing on October 13. A 'Frontline Command Post', positioned at Tsona, replaced Z419 for the battle.
The second meeting, at which the final go-ahead was given, took place at 1:30 pm on October 17.
The central military commission and Mao himself approved General Zhang's battle plan.
Besides the PLA's overwhelming advantage in combat soldiers numbers, Li's research reveals the Communist party's Tibet work committee supported the frontline with a major logistic effort.
It dispatched 1,280 party cadres to lead civilian workers functioning as logistical support teams.
32,237 Tibetans and 1,057 pack animals were drafted to load, unload and transport supplies, carry wounded soldiers back from battlefront, and clear up battlefields, etc.
Over 10,000 civilians were drafted to repair and construct roads.
It is hardly surprising that, on October 20, Indian defences in the Tawang sector crumbled in hours.