ON May 18, 1843, the General Assembly of the Church of Scotland was due to be convened in one of Edinburgh’s most elegant places of worship, St Andrew’s on George Street.

While a huge crowd waited outside, the retiring moderator, the Rev Dr David Welsh, professor of ecclesiastical history at the capital’s university, led a prayer to open proceedings. A roll-call should have followed. But Welsh stayed on his feet and, to a breathless hush, said: “There has been an infringement on the constitution of the Church, an infringement so great that we cannot constitute its General Assembly.”

He went on to read out a long protest against attacks on the Kirk mounted over the previous 10 years by the Parliament at Westminster. Redress had been sought in vain, so he and all who believed in the spiritual independence of the Church of Scotland had now no choice but to walk out of it. What he meant first and foremost was its right to appoint its own ministers. The Kirk said the congregations should elect them, but the law said lay patrons of parishes (usually landowners) could nominate them.

The Church regarded itself as a spiritual corporation, belonging to this world though with Jesus Christ at its head, so that it should be able to decide its own affairs for itself. But Parliament maintained the Church of Scotland, not to say Jesus Christ, must be subject to its own absolute sovereignty. At will, it could overrule the General Assembly, and had recently made a habit of doing so.

At St George’s, Welsh laid his protest on the table, turned and bowed to the royal commissioner, the Marquess of Bute, then stepped down from the chair and walked to the door. As he went, other ministers and elders got up from the pews to follow him, row after row of them.

Outside, the crowd first cheered them but then fell solemnly silent. Many more who had pledged to leave the Kirk waited in the street. Though no procession had been planned, the crush grew so great that they were forced to walk in column, three or four abreast.

READ MORE: SNP eye North Lanarkshire takeover after local elections

They marched to a hall prepared for them at Canonmills, a couple of miles away down the hill. There they constituted themselves the Free Church of Scotland. The Rev Thomas Chalmers was elected its first moderator. About 450 ministers, 40% of the Kirk’s clergy, signed a deed of demission giving up their charges, manses and incomes. Nearly half the laity all over Scotland would join them in declaring independence.

“Well, what do you think of it?” a friend asked Francis Jeffrey, judge and journalist.

He replied: “I’m proud of my country. There is not another country on Earth where such a deed could have been done.”

The issues behind this breach in national life are so remote from today’s concerns as to be scarcely explicable to modern Scots. They turned on much more than legal technicalities or relations of church and state. Ever since the Reformation of 1560 a continuum had been sustained in those relations, with even the Union of 1707 making little difference.

In Scotland at least it was widely accepted that the state looked after temporal concerns and the church took care of spiritual concerns, widely defined to include education, care of the poor and curbs on the Scots’ sins of drunkenness and fornication.

Collisions between church and state often took place, but the two sides gradually came to terms and in the late 18th century reached equilibrium. It relied on a circle round the Rev William Robertson, principal of the University of Edinburgh during the high Enlightenment. He organised his clerical colleagues so well that they could regard themselves, and be regarded, as a party in the General Assembly, with the winsome name of Moderate Party.

Several of the circle – the Revs Hugh Blair, Adam Ferguson, John Home and Thomas Reid – were themselves leading enlightened intellectuals. Under their guidance, the Kirk behaved itself as a polite member of civil society and in return got its constitutional privileges respected.

Yet there had also been steady dissent and secession from Robertson’s kind of Kirk. New, independent congregations formed among those who disagreed with it, and drops of its life’s blood drained away into each of them. Slow death beckoned.

It was not that a new generation of Presbyterian leaders remained blind to the dangers. To the fore was Chalmers who, after ministries in Fife and Glasgow, became professor of divinity at the University of Edinburgh in 1828.

For him, preserving the Church of Scotland meant preserving its role not as a mere reassurance and support to its members but as the saviour of society, guardian of its morals, teacher of its children, protector of its poor.

Above all, a religious establishment needed to extend into the booming cities of industrial Scotland and build many more places of worship for the submerged proletariat. Where would the money come from? Chalmers’s bright idea was the British state, which turned him down.

While demanding this support, he also refused to submit to any kind of supervision: the Kirk needed freedom of action to meet its challenges. The conflict inherent in his analysis led to crisis. The state would not concede any control, and the Disruption followed as an act of defiance.

Chalmers claimed victory after May 18, 1843, yet he fooled himself. His vision for Scotland depended on a religious establishment.

In fact he caused its collapse. For the four years of life left to him, he in effect strove rather to prove the Church was better off without the state.

So it might have been in worship or discipline, yet the key to its future lay in the social role he always stressed. In person, he sought to run in Edinburgh’s slums an experiment in welfare on the voluntary principle, where the rich looked after the poor but the poor were also expected to look after themselves as far as they could.

The National: National Extra Scottish politics newsletter banner

A new system should rely not on taxation and redistribution but on discipline and self-help. Chalmers did actually try a practical experiment on these lines in a poor district of the capital, but had little to show for it.

The actual achievement had been to smash the equilibrium of Church and state in Scotland.

On one side of the scales established religion dropped away, now unable to perform its appointed social tasks. The balance then fell down on the opposite side, the side of the British state, the only other entity equal to those tasks.

Its influence proved to be an anglicising one.

Chalmers tried to lead a popular, evangelical revolt against these handicaps. In fact Scotland, with a vital element of its identity gone, had to adjust to a less autonomous position in the United Kingdom. It began to feel more like a province than a nation.

We might read into the Disruption a presage of later Scottish nationalism, in the rejection of the absolute sovereignty of Parliament. But the ancestry was indirect, and the Disruption’s leaders took care to play down any nationalistic aspect.

Rather, it was the social evolution of a more British Scotland, which few Scots wanted but all found inevitable, that sowed the seeds of later discord.