The high point of the 19 Shastri months was the 22-day war that he fought against great odds and won in principle, even if military historians often call it a stalemate.
Pakistan saw a great opportunity to conquer Kashmir and lost. It was the last time they had the relative strength militarily and diplomatically to take Kashmir.
Shastri's resolve buried that dream forever, points out Shekhar Gupta.
Two tumultuous 19-month periods have defined our past over three generations, determined our present, and will continue to dominate the future in their very contrasting ways.
One is easy to guess -- the 19 months of Emergency between June 25, 1975, and March 21, 1977.
One set of 19 history-defining months out of the way, can you guess what would be the second? I can make it easier for you.
Go back to the tenures of our prime ministers. Not Nehru, Indira, Vajpayee, Modi, V P Singh, Gowda, Gujral, Charan Singh. None of these.
Since I have already given the riddle away, I will now suggest that we read the just-released biography of Lal Bahadur Shastri, written by eminent former IAS officer-turned-scholar Sanjeev Chopra.
I had the honour to be among those speaking at the release of The Great Conciliator: Lal Bahadur Shastri and the transformation of India at the national capital's India International Centre.
Between June 9, 1964, after Jawaharlal Nehru's death, and his own tragic passing at Tashkent on January 11, 1966, Shastri also served for exactly 19 months.
And why do we argue that these were as consequential for India's political evolution as the Emergency, if in entirely contrasting ways?
Think of a mere 19 months when India fought a full-fledged war (September 1965), engaged in a localised skirmish with tanks (Kutch April-July 1965), dealt with crippling food shortages, navigated a difficult political transformation, and built more institutions than in any comparable period in our history.
The high point of the 19 Shastri months was, of course, the 22-day war that he fought against great odds and won in principle, even if military historians often call it a stalemate.
A stalemate against a much, much better-equipped enemy, with superior capabilities in every dimension of warfare -- often at least three notches higher -- is a victory.
Plus, only one side, Pakistan, had an objective in that war. They saw a great opportunity to conquer Kashmir and lost.
It was the last time they had the relative strength militarily and diplomatically to take Kashmir. Shastri's resolve buried that dream forever.
The legacy of Shastri is unfairly overshadowed by the peace he made at Tashkent -- a visit that also took his life. His true contribution is the war he waged.
Field Marshal Ayub Khan and his sidekick Zulfikar Ali Bhutto saw great vulnerabilities in the Indian armed forces reeling under the 1962 debacle, and now caught in frenetic transition.
They were emboldened by the 1963 Hazratbal crisis in Srinagar, misread the political transition from Nehru to Shastri as political instability, and then tested India's preparedness and morale with probing raids in the Rann of Kutch (RoK).
As Mr Chopra tells you in his very well-documented account, the Pakistanis also checked out their American masters' response by using the Patton tanks in RoK.
Under their larger agreement, they were not allowed to use them against India.
But, because the Americans did nothing more than make some pious tut-tuts, they knew they could make the big move on Kashmir.
The result: Just a couple of months later was Operation Gibraltar, which involved sending more than 10,000 armed infiltrators into Kashmir.
It was named Gibraltar because that was the first foothold the Islamic conquerors established in Europe.
Each infiltrating group was also named after famed Islamic warriors: Tariq, Qasim, Khaled, Salahuddin and, for sure, Ghaznavi.
Once these groups pulverised the Indian forces in the Valley, the decisive blow would be Operation Grand Slam, as Ayub named the planned massive tank thrust to take Akhnoor in Jammu, or going for the jugular, as he called it.
He is also recorded as having boasted that 'it is well known that the Hindu morale cannot survive more than one or two hard blows'.
In this case, there was also a misreading of the resolve of the leader on the other side.
Generals, especially Pakistanis, always have a low opinion of civilians.
Given how the thought processes of Ayub and his cohort worked, Shastri's diminutive stature and soft-spoken style strengthened this delusion.
Except that inside that frail 5ft 2in frame resided an incredibly strong-willed Indian patriot.
The increasingly successful fightback against the infiltrators was still on when Shastri convened his Cabinet on September 3.
With Pakistani tanks (Op Grand Slam) threatening Akhnoor, the broad outlines of his response were drawn.
Significantly, it included destroying Pakistan's offensive power while capturing only the minimum territory necessary and returning it after successful completion of the war.
There's much unanimity in India on the outcome of the war.
In India, the sore point will also be the return of the Haji Pir Pass in the Uri sector.
The UN ceasefire resolution, however, had demanded that both sides return to the Ceasefire Line as it existed on August 5.
This meant the Pakistanis had to vacate Chumb too.
While Pakistan lost its last chance to grab Kashmir, the tactical and territorial picture wasn't as one-sided as Indian folklore often suggests.
That's what caused the Haji Pir compromise and, probably, cost Shastri his life at such a young age.
From whispers in 1966 to WhatsApp in present times, Shastri's death has been one of those eternal mysteries and the subject of countless conspiracy theories.
The book gives us clarity on two things.
One, that Shastri had already had two heart attacks, in 1959 and then on June 5, 1964, within days of taking over as prime minister.
This was the era before statins, stents, bypass surgeries.
A third heart attack would be that much tougher to survive.
And the second, that on the day he signed the Tashkent agreement, Shastri was initially cheerful.
But as he heard of reactions back home, -- the 'surrender of Haji Pir' having become the refrain in the press -- and finally when he spoke with his daughter and wife, both of whom seemed unhappy, his spirit dropped. Within hours he was gone.
It is ironic and also quite tragic and unfair that while talking about Shastri's legacy, we get bogged down with that war and peace.
Or, in the overwhelming 'Jai Jawan' story.
His even more long-lasting contribution was on the 'Jai Kisan' front.
He initiated the Green Revolution, found C Subramaniam as his food minister, talent-hunted scientist M S Swaminathan, and founded India's first central agriculture universities.
More importantly, he reached out to the Americans for collaboration.
One of the lesser-appreciated aspects of Shastri's politics is that he wasn't a man of the Nehruvian Centre-Left.
You could call him a man of the Centre, as Mr Chopra does.
I would say he was more a leader of the Centre, but leaning a bit to the Right.
For evidence, read about his dismay at Nehru blocking Purshottam Das Tandon's election as Congress chief, his upbringing at the Servants of People Society, and his learnings from Lala Lajpat Rai.
And then, consider the backing he received from the decidedly right-wing and pro-West Swatantra Party during his first no-confidence motion.
Also, check out his speech where he locked horns with his Communist antagonist Hiren Mukherjee's accusation that he has deviating from Nehruvianism.
In essence, he said, deviation is what you complain about in the communist system. In democracy, there is change.
There is one enduring Americanism I repeat often: The only legacy you leave behind is people. In the case of Shastri, I will rephrase that.
An even better legacy for a great public figure to leave behind is the institutions they built.
The next time you hear the words PMO, CBI, CVC, Agricultural Prices Commission or even the BSF (Border Security Force), think Shastri.
It is all of these, besides that war and peace, that make his 19 months even more consequential for our present and future than the Emergency.
By special arrangement with The Print
Feature Presentation: Aslam Hunani/Rediff.com