On the night of 7 March 1965, NBC stopped its broadcast of the movie Judgment at Nuremberg to show news footage just in from Alabama. On a bridge en route to the state capital, unarmed civil rights marchers had been clubbed bloody by law enforcement, armed with night sticks, tear gas and barbed wire. Two weeks later, another march managed to reach Montgomery, because a furious President Lyndon Johnson had deployed the state’s National Guard to protect them, over the head of its Governor, George Wallace.

In recent days, this moment has been much invoked, because – until last Saturday – it was the last time a president overrode a governor to ‘federalise’ the National Guard, bringing it under direct control from Washington, DC. The US press has been reassuring readers that this is very rare – but that was not so in 1965. By then, America was a decade into the struggle of the white South to defy the Supreme Court’s 1954 ruling against educational segregation, compelling presidents of both parties to deploy armed force. At Little Rock, Arkansas in 1957, Eisenhower had deployed the Guard – and the 101st Airborne Division – to escort nine black children to school, in defiance of a racist mob. In 1962 at a university in Mississippi, and at another the next year in Alabama, Kennedy had done much the same.

One reason why the National Guard is a recurring player in these distinctively American stories is that – uniquely among the many branches of the US military – it can fall under the command of both state governors and the president. This ambiguity has meant that it has been caught up repeatedly in confrontations between the state capitals and Washington, DC.

Those presidents who federalised the Guard in the civil rights era did so by invoking the 1807 Insurrection Act, which overrides a legal bar on the president deploying military force on US soil. But Trump has broken new ground: his proclamation did not invoke the Act, claiming to have found a legal way around doing so.

Trump’s approach only intensifies the ambiguity of the Guard’s position, just as his attitude to deploying it is oddly ambivalent. He toyed with invoking it in 2020 during the George Floyd protests, even allowing aides to draft a proclamation to that effect, but he acquiesced to the opposition of his defence secretary, and told an interviewer that ‘We can’t call in the National Guard unless we’re requested by a governor.’

However, on the campaign trail ahead of last year’s election, he told a rally in Iowa that, next time, he would act without waiting for governors to ask. That is exactly what he has now done in Los Angeles: denouncing the protestors as ‘insurrectionist mobs’, and calling in the Guard to protect the Immigration and Customs Enforcement (ICE) agents, whose round-ups triggered the demonstrations.

Yet his proclamation relies solely on the authority of Title 10 of the US Code, which is normally used in conjunction with the Act. Even Trump seems wary of actually invoking the Insurrection Act, which would permit the Guard to arrest American citizens.

The questionable justification for all this – Trump has since sent in 700 Marines as well – is that the LA protests constitute a ‘rebellion’. California Governor Gavin Newsom is contesting this claim, along with Trump’s failure to involve him in the decision. Unlike those oh-so-hard-faced southern governors of the 1950s and 1960s, Newsom is taking the president to court.

This points to the other big difference between Trump’s decision and those of Eisenhower, Kennedy and Johnson: the distribution of power. When they overrode governors to federalise the National Guard in Arkansas, Mississippi and Alabama, it was in defence of those states’ most disempowered citizens. In his broadcast reaction to the brutality at Selma, Johnson even echoed the civil rights slogan: ‘We shall overcome’. The southern governors, like Orval Faubus of Arkansas, may have insisted that their states had become ‘occupied territory’ under the ‘naked force of the federal government’, but it was clear who the tyrants really were. Before the 10,000 men of the Arkansas National Guard were brought under federal command to protect the nine pupils as they entered the Little Rock school, they had been happily deployed by Faubus to stop the pupils.

Today, by contrast, Trump is overriding a state governor to send the Guard to help oppose protestors, not protect them. This may be breaking new ground in legal and constitutional terms, but in terms of power, it is historically familiar.

In 1914, even before it was formally named in law, the National Guard was busy massacring the wives and children of striking miners encamped in Ludlow, Colorado: far from the only labour dispute in which it was called to intervene. And for many years after its heroic role at Selma, the Guard was often deployed by state governors against protestors, both violent and non-violent. When riots erupted after Martin Luther King was murdered in 1968, the Guard was called in across the country; in Delaware, they occupied Wilmington, the state capital, for over nine months.

A few months earlier, the Guard helped the 82nd Airborne Division defend the Pentagon from protestors marching against Vietnam. It was in preparation for the ‘March on the Pentagon’ that the Justice Department came up with the idea that the Guard could be legally deployed to defend federal property and functions – the untested theory on which Trump’s current deployment reportedly relies.

This phase of the Guard’s history culminated at Kent State University in 1970, when Guardsmen policing anti-war protests shot four young people dead. Nothing in its subsequent history has come close, ut Kent State reminds us that the spectacle of Guardsmen violently confronting peaceful protesters is far from unprecedented. And nor, as Selma reminds us, is a president deploying the Guard. What’s new is the spectre – if Trump does finally invoke the Insurrection Act – of both happening at once.