Power has to be relentlessly fought. Without being constantly checked, exposed, harangued, mocked and driven back, it would swiftly devour all the rights that were won at its expense. There is invariably a cost. The powerful know that if those who chip away at their authority are not undermined, or humiliated, or even persecuted, others would be emboldened to strike blows at them, too.

And so it is with Bradley Manning. Although a military judge has found him not guilty of aiding the enemy, the guilty verdicts on other charges will leave him languishing in military custody for much, if not all, of his life: indeed, he faces a sentence of 130 years. Here is the sacrifice he has paid for exposing the secretive actions of a government that claims to act in the name of the US people.

Here's why. Over a decade ago, the US initiated two calamitous wars in Afghanistan and Iraq, with a terrible human cost that is still paid every single day. The then-UN Secretary General Kofi Annan declared that the Iraq invasion was illegal; the country is today still awash with car bombings and gruesome sectarian bloodletting. It was always in the interests of the US elite to keep the consequences of their actions as far away from public consciousness as possible. The justification is that such secrecy is needed to protect the American people from the country's enemies. “It's for your own good” is the stock defence of every authoritarian. But the real aim is to stem opposition. Every US hawk still shivers at the photographs of naked Vietnamese children, faces contorted with panic, running with their skin burned after a napalm attack, which helped galvanise the anti-war movement of the 1960s and 70s.

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By being responsible for the biggest leak of classified information in US history, Manning revealed the sordid realities of a war that the armchair warriors want sanitised. Like an Apache helicopter, bombing the life out of Iraqi civilians and a Reuters journalist, the corrupted pilots dismissing their victims as “dead bastards”. He found evidence of US-backed death squads and militias operating in Afghanistan. He helped reveal the rampant corruption of the US-backed Tunisian dictatorship, who basked in luxurious homes and extravagant lifestyles while their people suffered grinding poverty, providing ammunition for the revolutionaries who toppled Ben Ali.

It would have been a farce if Bradley Manning had been found guilty of aiding the enemy. After all, it was not Bradley Manning who funded and armed Afghan jihadis in the 1980s, some of whom evolved into al-Qa’ida elements; it was not Bradley Manning who propped up the thugs, thieves and murderers who dress themselves up as the rulers of the Middle East, provoking the fury of millions; it is not Bradley Manning who unleashed the bloody mayhem of Iraq, which attracted swarms of Islamist car-bombers and throat-slitters. The US government officials who doubled up as recruiting agents for al-Qa’ida remain at large.

Nonetheless, there is an important moral victory in the verdict. Manning is a whistleblower, not a traitor. If revealing information that was portrayed as playing into the hands of the enemy was officially declared to be treasonous, it could have had a crushing impact on investigative journalism and political dissent.

The US whistleblower Edward Snowden will have watched the verdict carefully from his banishment in a Russian airport. If he is unable to reach Venezuela, which has granted him political asylum, and falls into the hands of the US authorities, he too will face a lifetime of incarceration.

The US government will hope that an example has been set; that future whistleblowers will be deterred from uncovering injustices committed in the name of the US people without their knowledge or consent. That is why it is so important to offer gratitude and support for the Mannings and Snowdens of this world, when they sacrifice so much in the interests of openness, transparency and freedom. Only that will inspire other whistleblowers who know that – while their liberty is imperilled – millions will be cheering them on.

It should not come down to brave, one-off individuals, of course. The struggle for open governments, who are honest about what they do in our name, needs a mass movement to be truly successful.

Bradley Manning explained his actions by saying he wanted a debate about Western foreign policy. As this 5 foot 2 soldier continues a life without any liberty, we owe him that much. Even many of us who opposed or even marched against the Iraq war, then turned our eyes when the blood and chaos began: it was all too complicated, too distant, too unreal. We shrug off the support of our governments for dictatorships who torture, maim and kill as though it is simply a fact of life. Another shipment of arms for Saudi Arabia's ruling thugs; another Afghan wedding party reduced to a pile of shredded organs and charred bones; a former Prime Minister working for a dictatorship, as with Tony Blair and Kazakhstan's tyrant. Sometimes, it barely even registers.

We shouldn't pity Manning. We should admire his courage, and be inspired by it to scrutinise what our governments do both here and in distant lands without even bothering to consult us. For us all to do our bit in a struggle for a more just world order: that would be the ultimate show of gratitude to Bradley Manning.