At the 1981 Labour conference in Brighton, Neil Kinnock found himself assailed by a young Tony Benn supporter in the lavatory of the Grand Hotel. The future leader was targeted for his refusal to endorse Benn’s failed deputy leadership bid. “I beat the shit out of him,” Kinnock later recounted. Those who surveyed the scene described seeing “blood and vomit all over the floor”.

Before Labour assembled in the same town for its 2015 conference, MPs spoke darkly of their fear of a return to such barbarousness. Jeremy Corbyn’s leadership has pitted the party’s “Tories” and “Trots” against each other. Yet the week passed without rhetorical or physical fisticuffs. After the election of a leader opposed by more than 90 per cent of MPs, Labour managed a passable impression of unity.

The scale of Corbyn’s victory explains this placidity. The defeated candidates acknowledge that a period of reflection is necessary before they can credibly challenge his leadership. To behave as if failure were inevitable (though most MPs believe it is) would only widen the chasm between them and the membership. While still bewildered by Corbyn’s election, many savoured the novelty of a conference that was free of “lines to take” and of collective responsibility. “It’s ‘a thousand flowers bloom’. We can say what the f*** we like,” a senior MP told me.

In other respects, the conference was familiar. The delegates had been selected and the fringe meetings arranged in the pre-Corbyn era. The titles and venues of the left’s events reflected its past marginalisation. Chairs apologised for overflowing rooms, quipping that they didn’t expect to be “running the party”. The conference was a bridge between the old world and the new. As they crossed the frontier, all sides armed themselves for the battles to come.

After failing to secure a conference debate on Trident, the left, operating through the Bennite Campaign for Labour Party Democracy, has vowed to raise its game next time. It will be countered by Labour First and Progress, the organs of the party’s self-described moderates. After Corbyn’s pledge to enshrine conference as Labour’s pre-eminent decision-making body, delegate selections will become a defining battleground. The leader’s supporters cite his mandate as justification for his “democratisation” of the party. MPs cite their own rival mandate from the British electorate. As the shadow minister Conor McGinn told me, “I’m not elected to be their delegate. I’m elected to be their representative and then elected to be an MP for all my constituents.”

Away from the fringe and the hall, the party’s ruling National Executive Committee was tilted to the left. The shadow foreign secretary, Hilary Benn, was removed in favour of a Corbyn supporter, Rebecca Long-Bailey, and the moderate trade union Community was defeated by the militant bakers’ union. On such seemingly obscure results could the Labour leader’s fate depend. Based on current guidelines, party officials say, Corbyn would not automatically make the ballot if challenged by a rival candidate. Rather, he would again require the endorsement of at least 35 MPs. Crucially, it is the NEC that determines party procedure in these circumstances.

After Corbyn’s shambolic opening week as leader, both his supporters and his opponents asked whether he would fall through sheer amateurishness. But after appointing a full front-bench team, in defiance of earlier predictions, and filling the main posts in his office, his position was stabilised. As the conference progressed, the number of MPs predicting that he would endure for a full term steadily rose.

Yet for Corbyn, greater security has come at a price. He has already made concessions on the EU (pledging to campaign for UK membership), Nato (no longer advocating withdrawal), Syria (allowing shadow cabinet members to support military action) and energy (abandoning his promise to nationalise the big six companies). The shadow chancellor, John McDonnell, avoided any mention of the divisive issues of “people’s quantitative easing” and the “Robin Hood tax” in his speech and vowed to vote in favour of George Osborne’s fiscal charter. “It has felt like a series of defeats,” one Corbyn ally confessed to me. Only in the case of Trident did the leader wield his mandate and advance a minority position – unilateral disarmament – in his conference address but what could be a trigger for shadow cabinet resignations may ultimately be resolved through a free vote for frontbenchers.

A popular theory in Labour circles is that Corbyn will voluntarily resign after two years, having achieved some internal reforms, and endorse a successor. Lisa Nandy, the shadow energy and climate change secretary, is the name most often mentioned, though she is from the soft left, rather than the leader’s harder wing. Those close to Corbyn, however, say that he is “enjoying” the job and is not planning an early departure. This did not prevent speculation in the bars of Brighton about the identity of the next leader. Dan Jarvis, Tom Watson, Yvette Cooper and Chuka Umunna were the names most commonly cited. Corbyn’s opponents acknowledge that their task next time will be to unite around one candidate and to back him or her unreservedly.

Next May, the Labour leader will face his first electoral tests in London, Scotland, Wales and England. Some MPs have earmarked this date as the first possible moment to strike. Others warn that this strategy could founder if Corbyn exceeds the low expectations. MPs’ greatest fear is that the issue of reselection will rise as they are blamed by the left for any reversals. McDonnell’s appeal to former shadow cabinet members to “come back and help us succeed” was interpreted by many as a threat.

After one of the most severe schisms in its history, Labour emerged from Brighton surprisingly unscathed. But underlying the calm was the fear that, by next year, there will be blood.