In pictures: The Conservative Party and Europe - a long and fractious history
Tory Brexiteers reacted with anger to comments made by Chancellor Philip Hammond in Davos on Thursday about the Government seeking "modest" changes to its relationship with the EU.
Mr Hammond has since walked back his comments after high-profile Brexiteer and colourful Conservative backbencher Jacob Rees-Mogg accused ministers of being cowed by the EU.
This isn't the first time the UK's relationship with Europe has caused tensions to rise inside the Conservative Party. Here we look back on the Tories' changing attitudes towards European integration over the years and the conflicts that ran alongside them:
1975 - Thatcher champions European trade
Then-leader of the opposition Margaret Thatcher campaigned passionately for the UK to remain in the European Community in 1975.
1992 - John Major battles with rebels
Sir John Major clashed with a group of backbench rebels over the implementation of the Maastricht Treaty into British law during his time as prime minister and Tory leader. One of those rebels, Norman Tebbit, called on Sir John to jettison the treaty during the Conservative Party Conference in 1992.
1999 - Labour stokes Tory divisions
Conservative divisions on Europe were exploited by Labour during the 1999 European elections. This Labour Party election campaign billboard showed the more Eurosceptic leader William Hague flanked by gagged Europhiles Michael Heseltine and Ken Clarke.
2000 - Strong opposition to the euro
With Labour flirting with joining the euro at the time, William Hague made opposition to the single currency a leading plank of Conservative policy during his time as leader. The Tories fought the 2001 general election using the slogan "In Europe but not run by Europe".
2016 - Civil war during EU referendum
Amid pressure from Ukip, David Cameron included a pledge to hold an in-out referendum on the European Union in the Conservatives' 2015 general election manifesto. Then-Tory leader, Mr Cameron played a leading role in the unsuccessful Remain campaign, while leadership rival Boris Johnson backed Vote Leave.
May 2017 - May accuses EU of interference
Prime Minister Theresa May caused controversy when she accused the European Union of deliberately trying to influence the result of the UK general election.
January 2018 - Infighting intensifies
Jacob Rees-Mogg led a Brexiteer revolt against the Government over its handling of Brexit negotiations amid rumours of increasing clamour from Tory backbenchers for a leadership challenge to Mrs May.