In a culmination of decades of infighting over Europe, Prime Minister Boris Johnson on Tuesday axed the lawmakers, some of them former ministers, after they voted against the government's hardline Brexit strategy.
Among those targeted were Philip Hammond, finance minister for three years until July, and Ken Clarke, parliament's longest-serving MP dubbed "the Father of the House".
Nicholas Soames, the grandson of wartime prime minister Churchill - widely considered the greatest Conservative leader - was also told he must now sit as an independent.
The cull, which could bar them from standing as Conservatives at the next election, came hours after Phillip Lee resigned to join the Liberal Democrats - the fifth ruling party MP to quit this year.
Conservative MP Nicholas Soames arrives at the cabinet office in London. Source: EPA
"Sadly, the Brexit process has helped to transform this once great party into something more akin to a narrow faction," he wrote in his resignation letter.
He noted the party was no longer the "broad political church" he joined as a young man.
"It has increasingly become infected with the twin diseases of populism and English nationalism," Lee said.
'Like something out of N Korea'
The Conservatives, one of the world's oldest and most successful political parties, have long been dominated by divisions over Britain's relationship with Europe.
The issue contributed to Margaret Thatcher's 1990 resignation after 11 years in power, while directly causing ex-premiers David Cameron and Theresa May to step down in the past four years.
But political historians say the current fractures - and the response to them -are different.
Pro-Remain protesters demonstrate outside Parliament in London. Source: EPA
"(It's) unprecedented historically, both in terms of the scale... and the threat of deselection coming directly from the leadership," said Nick Crowson, professor of contemporary British history at the University of Birmingham.
The sacking of such prominent Conservatives by Johnson, who had himself voted against the previous government twice earlier this year, has reportedly shocked even those working in Downing Street.
"It's like something out of North Korea," one aide told the Politico website.
"I honestly think they've completely overreached."
Wedge issue
It was not supposed to be this way.
Cameron called the 2016 referendum in a bid to unify his party behind continued EU membership, with Nigel Farage, then leader of the United Kingdom Independence Party (UKIP), ascendant in the polls.
But when Cameron lost the vote -- with 52 percent of Britons favouring Leave -- and he was forced to resign, Brexit became the defining issue driving an ever bigger wedge through the party.
May tried to promote consensus between the two rival camps, balancing her cabinet between Leavers like Johnson and previous Remainers such as Hammond.
However, her strategy failed as a string of Brexit hardliners resigned from the cabinet while moderates also left the government in disagreement.
In February, three Conservative MPs quit the party to join a breakaway group of pro-EU lawmakers from the Labour party, while another left to sit as an independent in April.
But with Brexit stalled amid opposition to the divorce deal that May struck with Brussels, voters deserted the Conservatives for Farage's new Brexit Party in European Parliament elections this year.
The party came a humiliating fifth in the vote, setting the stage for hardliners seized the initiative.
'Defend my party'
Boris Johnson became leader vowing to leave the bloc "do or die" on the delayed deadline of October 31, installing key figures in the victorious 2016 Vote Leave team in government.
This has left the moderates opposed to a no-deal Brexit in what Hammond called Tuesday "the fight of a lifetime".
"I am going to defend my party against incomers, entryists... people who are at the heart of this government who care nothing about the future of the Conservative party," he told the BBC.
Some political analysts believe predictions of the party's demise are premature -- but the Brexit-fuelled divisions will be tough to repair.
Oliver Patel, of University College London's European Institute said: "Whichever option (they) choose, a large part of the party will be against it, whether it's a deal, no deal or no Brexit."
