In the official celebrations, they tell us that ANZAC Day commemorates a fight for freedom. In reality, the First World War meant an extraordinary crack down on liberties in both Australia and New Zealand, the implications of which are still being felt.

As Jared Davidson explains in his new book Dead Letters: Censorship and Subversion in New Zealand 1914-1920, many European countries no longer required passports before the war. They were brought back into use under the security regime mandated by the conflict. ‘The First World War,’ he says,

was therefore a turning point in the history of mobility and citizenship, where the aspiration to control finally coincided with the actual ability to control, and once these were institutionalized they were not dismantled.

Davidson’s project centres on a particular institution of control – the censorship of mail, which was embarked on with considerable enthusiasm by the New Zealand authorities.

As in Australia, the state justified its wartime regime by invoking the threat of espionage and the necessity to protect battlefield operations. As in Australia, the censors concentrated less on military secrets than on policing dissidence. Davidson notes that, in twenty-four pages of quarterly reports by the Deputy Chief Postal Censor Walter Tanner, only twelve lines mention naval or military information of value to the enemy.

In proportional terms, New Zealand charged or jailed far more people for seditious or disloyal remarks than Britain did, a quite remarkable statistic given the country’s distance from the frontlines.

Then again, the war came immediately after the 1913 Great Strike, one of the most intense industrial disputes in New Zealand history. Not without reason, the state worried about its ability to maintain control.

For his epigraph, Davidson cites Ha Jin’s observation that war ‘reduces human beings to abstract numbers’. However, that abstraction – the transformation of candid communications into evidence – gives the historian access to intimacies that wouldn’t have survived in other circumstances.

In a card dated 7 April 1918, for instance, a miner by the name Frank Burns expresses surprise in learning of a friend’s marriage. He asks:

Say, Doll, what kind of bloke is he. I hope he is not a bloody policeman, if he is, don’t answer this letter, and let me forget you forever, for Christ’s sake, leave the buggar, separate get a divorce or do anything rather than marry one of those useless, good for nothing mongrels.

Burns had evaded conscription by hiding in the bush, and was then been sentenced to two months with hard labour in Westport jail. Having reached the bottom of the paper, he jokes, ‘half time, turn over’, and launches cheerily into another anecdote with, ‘well my lovely bunch of sun-drops, I have got a little experience … to relate.’

The letter conveys as much through style as substance, providing a glimpse of the everyday working-class humour rarely registered in official documents.

Davidson takes Burns letter to his ‘Doll’ from the magnificently titled Army Department’s Secret Registry. Only a fraction of the letters surveilled by the authorities remain intact but they’re still sufficient to offer a window into the vanished world of pre-communist radicalism.

Take the letter addressed from ‘J Sweeny’ on 3 November 1915, which includes the following passage:

I have been in the back country for the last 10 weeks had 4 inches of snow in two days in camp had to clear a track from the tents to cook house had very rotten Has mouse dung in the flour and sugar.

The text reads like an apolitical account of rural deprivation – but then it concludes, ‘I am yours for Direct Action No Political Dope.’ That complimentary close identifies J Sweeney as a supporter of the Industrial Workers of the World, the revolutionaries who blended European syndicalism with American hoboism.

In Auckland, Davidson tells us, the IWW established ‘The Workers’ University Direct Action Group’, which they advertised – with typical elan – as required to ‘educate the mentally lazy and those who, by over-work, are shamefully robbed of that nerve force or energy so necessary for educational advancement.’

‘Spittoon philosophers and gasbags anchor outside,’ the Workers University flyer continued. ‘We want no wet blankets’.

In Australia, the IWW was banned and its leading cadre imprisoned. In New Zealand, the group remained legal but its members were often deported.

We know very little of J Sweeney, not even his first name. But even that brief letter gives a sense of how IWWism shaped the lives of militants. With his ‘No Political Dope’ valediction, he reaffirmed both his opposition to parliamentarianism and his commitment to the distinctive Wobbly lexicon.

The potted biographies Davidson constructs from the registry present wartime dissidence in all its diversity.

‘They tell us to fight for king and country,’ declared Māori leader Te Kirihaehae Te Puea Herangi. ‘We’ve got a King. But we haven’t got a country. That’s been taken off us. Let them give us back our land and then maybe we’ll think about it again.’

The rhetoric of Timothy Brosnan, an Irish Catholic road labourer court-martialled for resisting conscription, sounded remarkably similar. In a letter, he explained the answer he gave to the court that asked him to put on a uniform: ‘I said I was an Irishman, a Sinn Feiner … that I would never fight for John Bull but always fight against him.’

The registry also contains a 1916 letter from a certain Marie Weitzel to her brother in Germany that presents the hostility to John Bull from a different direction:

The English and their greed, are the roots of all misery that prevails in the world. … It is awfully lonely to be in this country, the only Germans among the worms, the only ones with a heart.

The anti-German sentiment in New Zealand pre-dated the war, with the colonies reflecting and intensifying hysteria emanating from the imperial centre. In 1909, with Britain engaged in naval arms race with Germany (and readers thrilling to HG Wells’ recent The War in the Air), a wave of Zeppelin sighting swept across New Zealand. At the town of Kelso in West Otago, a teacher and two dozen students swore that they’d witnessed a German airship swooping over the town, sending police scurrying to investigate.

The outbreak of hostilities intensified the terror of outsiders. Yet Weitzel came to the censor’s attention, not merely as a German but as a socialist.

In 1912, after losing court cases resulting from squabbles with her neighbours, she asked a local minister why she had been robbed of justice. He replied that socialists and anarchists had no right to justice.

The Women’s Anti-German League declared Weitzel ‘a dangerous person’ on the basis of the (actual) presence of visiting radicals in her family home. ‘Meetings are held there by the Socialists and the IWW,’ they declared.

As a result of the persecution she faced, Weitzel requested, at the end of the war, to be repatriated to Germany, only to be told that she wasn’t eligible … because of her British citizenship. The official who refused her request concluded:

the letter is couched in such an impertinent typically German manner that I think the applicant condemns her case at once.

But you didn’t have to share the nationality of the enemy to face racial persecution combined with bureaucratic obduracy. Another letter comes from a man called Arthur Muravleff, desperately seeking release from the Somes Island Internment Camp. Muravleff was Russian, and although the Russians were allies, they were considered foreign enough to be suspicious. In his correspondence, he sought, unsuccessfully, to find precisely what he’d done to warrant incarceration.

‘Please inform this Prisoner of War,’ wrote an officer in response, ‘that the Defence Department does not feel disposed to furnish him with full particulars for which he was interned.’

Muravleff was instructed to write to Peter Simonov, the Russian consul in Melbourne. But Simonov had also been imprisoned (by the Australian government, for his Bolshevik agitation) – and so Muravleff remained imprisoned until he escaped in 1920.

Dead Letters contains a striking photograph of a further Somes Island detainee – a woman by the name of Dr Hjelmer Dannevill, under suspicion of being a German spy but investigated mostly for her sexuality.

In the image, she wears a long skirt but also male boots, jacket and tie, with close-cropped hair. The authorities could determine neither her nationality nor her gender. They interrogated her about the first – and medically examined her to decide the second.

The registry holds letters confiscated from Dr Dannevill, in which other women shower her with endearments.

‘Oh my Hjelmar I do want you so,’ writes one. ‘I must let my heart’s love flow out to you in writing it will relieve me.’

The slim documentation surviving about her case includes an article from the Wellington Evening Star reporting that ‘the voice of gossip has insisted for a long time past that this lady, who claimed to be of Danish nationality, would find more congenial company on Somes Island’, and a letter from a Mr JA Fothergill of Dunedin expressing his gratitude for Dr Dannevill’s medical skills and defending her ‘masculine style of dress’ as ‘merely a proof that her mind had risen superior to and emancipated from the tyranny and vanity of fashion.’

The First World War ushered in new modes for thinking about sexuality and politics. Dead Letters captures a moment of transition, an instant in which ideas we now take for granted still contended against ideas now forgotten.

Take the 1919 correspondence from Laura Anderson in Auckland to her cousin Sara in Denmark, in which Laura discusses the enthusiasm she and her husband Carl feel for the Russian revolution. She writes:

We are both very much interested in the Bolshevik movement in Europe, but there are so many contradictory reports in our newspapers that it is hard to know what to believe. No doubt you get more reliable news on account of living in a neutral and democratic country, and I would very much like to hear your opinion of the Bolshevik Governments. My husband … has written a poem about “Bolshevism” and we would like to send it to Lenin or Trotsky, but on account of the strict censorship we are unable to do so from here. If I sent the poem on to you; would you be able to address and send it on to either of them at Moscow.

We don’t tend to think of New Zealand as less democratic than Denmark but – less than a fortnight after Anderson posted her letter – it was being read by the Deputy Chief Postal Censor.

‘I should judge that the husband is a Bolshevik sympathizer,’ he, rather redundantly, concluded.

In fact, Carl Anderson was more than that. He and Laura farmed dairy on a remote property west of Auckland but Carl was also a visionary known as the ‘Mystic of the Waitakeres’, who believed he channeled cosmic forces with his poetry.

As for Laura, she was the daughter of a spiritualist, whose nephews founded the ‘Beeville’ commune in 1927, where pacifists, nudists and vegetarians forged an alternative lifestyle long before the sixties counterculture.

The intercepted letter of 1919 marks a time when the meaning of Bolshevism was still perceived as sufficiently in flux that Lenin and Trotsky, though embroiled in the Russian Civil War, might welcome some verses composed by a mystical farmer-poet at the other end of the world.

In places, the chronological jumps in Dead Letters make for challenging reading for those unfamiliar with New Zealand labour history. Yet, if you push through the difficulties what emerges – as Charlotte MacDonald says in her introduction – is ‘a map of radical New Zealand c1914-1920 and its connections with the wider world.’ The stories we hear might be framed by repression, but they speak about forgotten yearnings for political change.

Dead Letters: Censorship and Subversion in New Zealand 1914-1920 by Jared Davidson is published by Otago University Press.