For more than 150 years, the Tata Group has been synonymous with India's nation-building project, venturing into everything from autos to airlines when the country needed it.
And no executive better personified India's emergence on the world stage than Mr Ratan Tata, its chairman emeritus, whose string of dazzling takeovers took a largely domestic firm global.
Now the group's legacy is under threat.
An internecine war over the conglomerate's future took a crippling turn on Wednesday, reported Bloomberg.
In a surprise ruling, the National Company Law Appellate Tribunal (NCLAT), said Mr Ratan Tata's erstwhile successor, Mr Cyrus Mistry, was improperly ousted as chairman of the group's holding company three years ago, paving the way for his reinstatement.
In a further blow to the elderly tycoon, the court found the group's move to restrict Mr Mistry's family from selling out of the holding was unlawful and must be reversed.
The Tata Group can appeal the ruling to the Supreme Court. But the turmoil could not have hit at a worse time for the US$110 billion conglomerate, whose products range from salt to software.
It comes just as the group contends with a crisis at its British unit, Jaguar Land Rover Automotive - one of the crown jewels of Mr Ratan Tata's buying spree - and a crushing economic slowdown at home that's dampened demand for wares from steel to Tetley teas.
Mr Mistry, who had alleged shareholder oppression and mismanagement at the holding company, called the judgment "a victory for the principles of good governance and minority shareholder rights".
"The outcome of the appeal is a vindication of my stand taken when the then board of Tata Sons, without warning or reason, removed me, first as the executive chairman and subsequently as a director of Tata Sons," he said.
Tata Sons said the company would take appropriate legal recourse.
It also said that it has always operated in a "fair and equitable manner" and "acted in accordance with the law and will continue to do so".
In a letter to employees, chairman N. Chandrasekaran, who was appointed in February 2017, urged everyone to stay focused on the business and the welfare of stakeholders.
Mr Mistry had contested his removal as chairman, accusing the group of not following due process and alleged inappropriate interference in the company's affairs by Mr Ratan Tata.
The NCLAT two-judge bench in its 172-page order sided with Mr Mistry. It deemed the appointment of Mr Chandrasekaran illegal and asked Mr Ratan Tata not to interfere in matters.
The tribunal also ordered that Mr Mistry be reinstated as director of Tata Group companies.
"It is a landmark ruling underlining the need for a board to be the effective institution for governing a company," said Mr Somasekhar Sundaresan, an advocate representing Mr Mistry.
The clash between Mr Mistry and Mr Ratan Tata has been one of the most high-profile and publicly fought corporate battles in India.
Mr Mistry is a scion of the Shapoorji Pallonji family that holds a minority stake in Tata Group.
Tata Trusts, a group of public charities, owns a controlling 66 per cent stake in holding company Tata Sons and is chaired by Mr Ratan Tata.