It was the apparent change of heart that drastically changed a $4.6 billion, 25,000-employee grocery chain.

A London woman, a widow once married to a Demoulas brother, made a decision in June 2013 that led to a domino effect that has changed, potentially forever, Tewksbury-based Market Basket.

The sequence of events started by Rafaela Evans has led to one major change after another: She switched allegiances from one side of the Demoulas family to the other, leading to a shake-up on the board of directors that oversees key aspects of the company, which led to a controversial $300 million special payout to family shareholders, and, ultimately, the ouster last month of popular CEO and 40-year employee Arthur T. Demoulas.

Evans’ decision tipped the seven-member board of directors from Arthur T. Demoulas’ favor to that of his cousin and rival, Arthur S. Demoulas.

Each side of the family appoints two directors, with three independent directors chosen at a majority vote of all shareholders. All three independent directors are said to vote with the Arthur S. side of the family.

Only nine individuals own shares of the company. They are all descendants or in-laws of descendants of two brothers — George and Telemachus “Mike” Demoulas — who ran the company for decades. Evans was married to Evan Demoulas, the brother of Arthur S.

When Evan died in a car accident in 1993, his widow inherited his shares.

Each shareholder has typically stayed affiliated with one side or the other — either the side associated with Arthur T. or with Arthur S.

Evans, however, had for years voted with Arthur T.’s side of the family, giving those shareholders a majority and therefore control of the board.

Then she changed her mind.

Evans, who owns just over 4 percent of the company’s shares herself and is a shared trustee for another 1.5 percent, did not return a request for comment through her New York-based attorney.

A lawsuit filed in April cited the switch in allegiance and what it brought.

“The shift portended the ascendancy of the non-working half of the Demoulas family to corporate control and satisfaction for their pent-up lust for cash,” two directors affiliated with Arthur T.’s side of the family said. “That drive was apparently insufficiently attended to during the decade that the operating side of the family … had reinvested some of the profits of the company toward growth and survival in an increasingly cutthroat industry.”

Market Basket has been in the news more than ever in the past week but the Demoulas family battles go back decades.

After George Demoulas died in 1971, Telemachus continued operating the company. According to lawsuits, Telemachus hoarded more and more shares of the company away from George’s heirs. A lawsuit against Telemachus by George’s children found Telemachus liable for fraud, conversion and breach of fiduciary duties.

As a result, George’s heirs were given a slight majority, with 50.5 percent of the company’s shares.

Several lawsuits kept the family fighting over the years, including a widely reported punch that Arthur T. threw at Arthur S. in the back of a courtroom.

While Arthur T. had been at Market Basket for more than four decades, his cousins on the competing side of the family have gone into other areas.

Arthur S.’s address of record and company email corresponds with Ten Mountain Capital, a firm based on Newbury Street in Boston. Just one block over, on Commonwealth Avenue, his sister, Fotene Demoulas, is a principal with the interior-design company Fotene Design. Another sister, Diana Merriam, runs Merriam Vineyards with her husband, Peter, in California’s Sonoma Valley.

Family infighting went quiet for several years until last June.

Once Evans switched the side of the family she voted with, a domino effect followed.

Arthur T.’s side of the family saw the writing on the wall. In an editorial-board meeting with The Sun, he called the expected board vote “a predetermined assault.”

“Not any of them know the culture of this business here,” he said that day, one of very few public comments he has made during the power struggle.

The Arthur S. side of the family alone had received more than $500 million after taxes in dividends in the preceding 12 years, he said, “and it’s not enough.”

“If they remove me,” Arthur T. said, “what kind of message is that to the company?”

In other signs of what Arthur T’s side saw coming, one of its two directors, Charles Roazan, resigned only days after he was elected, according to a lawsuit. His replacement, William Shea, and Sumner Darman, the other director elected by Arthur T., said they couldn’t attend the next scheduled meeting.

Arthur S.’s shareholders sued, alleging that Shea and Darman were purposely missing the meeting so the board wouldn’t have enough participants to make a vote. They allegedly knew Arthur T.’s ouster was around the corner.

A Suffolk Superior Court judge ruled that Shea and Darman were required to attend.

Success story

By almost any measure, Market Basket had great success when Arthur T. led the company starting in 2008.

Sales grew from just under $3 billion a year to more than $4 billion, Arthur T. told The Sun last summer. The number of employees grew from 14,000 to what is now a reported 25,000. He kept a popular employee profit-sharing program and kept Market Basket at the basics: no website, and not even self-checkout lines, as other supermarkets have, because Arthur T. said he wanted “a human being waiting on a human being.”

That success also came at a critical time. Last summer, Stop & Shop announced it was closing all six of its New Hampshire stores, and Shaw’s said it would close six stores in New Hampshire and six others in Massachusetts and Rhode Island. At the same time, popular low-cost grocer Wegmans is making its move into the Boston area, including a store in Burlington planned to open this fall.

But the other side of the Demoulas family and their associated directors on the board felt differently. They said Arthur T. was “openly defiant” of the board, had a “dictatorial” management philosophy, withheld information from directors, let profit margins erode, and made illegal business deals with a company owned by his wife and brothers-in-law.

In a 2009 meeting, he allegedly told directors, “My style is not to come back to this board and ask for permission. I’m going to do it.”

At another meeting, in August 2012, he seemed to imply he was not accountable to the board.

“There’s not two. There’s not three. There’s not five,” he said, according to meeting minutes. “There’s only one boss in the company.”

In July 2013, at the board’s first meeting after majority control switched hands, as many as a thousand Market Basket employees and other supporters lined a road leading to the Wyndham hotel in Andover, where the meeting was being held, to show their support for Arthur T.

Arthur T. survived a 12-hour-plus meeting when the board decided not to make a vote on its CEO. The Arthur S. side of the family still controlled the board, however, and more changes were to come.

In August, the board voted to approve a $300 million special dividend for shareholders, a decision Arthur T. strenuously cautioned against. The board also voted to replace two of the three trustees overseeing the company’s popular longtime employee profit-sharing plan, and hired an executive search firm, a sign many saw as another precursor to Arthur T.’s removal.

In yet another lawsuit, Arthur T. sued his cousin, claiming that the $300 million dividend and other votes by the board were void because one of the independent directors, Keith Cowan, used to be one of the directors chosen by Arthur S.’s side.

The judge sided with Arthur S., and the dividend and other votes were allowed.

More legal woes

Predictably, more lawsuits were still to come.

In March, a real-estate developer sued the chain for allegedly failing to honor a commitment to build an access road at the development where it has a store in Londonderry, N.H.

In April, Arthur S.’s side of the family sued the two directors elected by Arthur T.’s side, alleging that they boycotted a meeting in March. Days later, those directors, Shea and Terence Carleton, filed a lawsuit of their own, saying they had been “marginalized” since the makeup of the board changed in June 2013, when they were suddenly in the minority.

Arthur T.’s removal in June was the biggest result of Rafaela Evans’ switch, as well as what rallied thousands of employees and pushed the family infighting into a major regional story. It brought its own domino effect: Two other executives were also fired, and seven executives with a combined 277 years with the company quit in protest.

On July 20, eight longtime workers with a combined 280 years with the company were fired because of what the chain’s new co-CEOs called “significant actions that harmed the company and therefore compromised Market Basket’s ability to be there for our customers.”

Now, Arthur T.’s side is making a play to buy out the competing side of the family. Dollar figures were not released, though the board of directors said it is “seriously considering” the offer.

There is one other way Arthur T. and his side could regain control. Someone — like Evans — could again switch sides.

Follow Grant Welker on Twitter and Tout @SunGrantWelker.