This is the third volume of Alastair Campbell's blockbuster diaries. It covers the period from May 1999 to September 2001, from the war in Kosovo to 9/11  the event that changed everything. As with earlier volumes, the pace is relentless. So much so that it is exhausting even to read about, never mind to have lived through.

Feeding frenzies and crises come and go, but certain themes underlie the entire opus: how to handle Gordon Brown and his rival court; the war of the women (Cherie Blair versus Anji Hunter); Philip Gould and his wretched focus groups. Gould was forever popping up with doom-laden, angst-ridden memoranda which always seemed to leak. New Labour was forever talking itself into crises that did not exist. One has periodically to pinch oneself to recall that, at the end of all this, they were re-elected with a majority almost identical to the landslide of 1997. They must have been doing something right.

Other long-running themes include control freakery (the foolish attempts to veto Ken Livingstone's London mayoral candidacy and Rhodri Morgan's leadership of the Welsh Assembly) and the fate of Peter Mandelson, to whose management a good deal of space is devoted. This volume covers his second enforced resignation, the tears, tantrums and the considerable fallout that followed as the Great Ingratiator attempted to claw his way back into favour.

Then, of course, there is Ireland, always in the background, as Blair attempted, with infinite patience, to bring the warring parties to the table and keep them there. It was not until his last days in office, six years later, that he succeeded. Peace in Ireland, a prize that had eluded all British prime ministers for 100 years, is surely one of the Blair government's greatest, most unsung achievements and one that deserves to be weighed in the balance against the failures of later years.

There are a handful of what Campbell refers to as 24-carat crises. Kosovo is one. As this volume opens, Blair is attempting to persuade reluctant allies that bombing alone will not bring about the defeat of Milosevic and his ethnic cleansers. The problem is that the Americans (shades of Libya?) are unwilling to commit ground troops. Blair, as he was later to do in other conflicts, has gone way out on a limb. The tension is considerable. At one point President Clinton lets fly at Blair for a full 10 minutes over the suspicion that the Brits are briefing against him. Mercifully, the mere threat of ground troops, plus the bombing of Belgrade, eventually persuaded Milosevic to back down, but it was, to quote the Duke of Wellington, a damn closerun thing.

The other 24-carat crisis recounted here is the petrol tanker drivers' strike in the autumn of 2000. This was arguably the greatest crisis of New Labour's first term. Until that moment, Blair had seemed invincible. Suddenly, all New Labour's many enemies  huntsmen, farmers, hauliers, tabloids  sensed the government's vulnerability and piled in. Odd things happened. The oil companies seemed strangely reluctant to resume supplies, even when the blockades were cleared. The police, to begin with at least, were curiously inactive, on occasion even providing escorts for the blockaders as they made their way down the motorways at five miles per hour. Over and over, Blair and Campbell can be heard comparing the softly-softly police response to that meted out to the miners in the 80s. Eventually Blair got a grip and the protests melted away as quickly as they had flared but, like Kosovo, it was a close shave and for the first time in a decade the Tories briefly moved ahead in the polls.

The other defining moment recounted here was when Blair was slow-hand-clapped by the massed ranks of the supposedly non-political Women's Institute, in the summer of 2000. This marked the death of the idea that there was room for everyone inside New Labour's big tent. It is unclear whose idea it was for Blair to address the WI, but Campbell and other advisers were nervous about it from the start ("over-pandering to what he thought a certain constituency wanted to hear").

This is a warts and all account. Campbell spares no one, not even himself, although there is occasional self-indulgence ("Guthrie... paid a nice tribute to me"; "John Keegan said he agreed with everything I said"; "A terrific leader in the Sun which said I was brilliant"). He enjoyed total access. His feet, unlike those of his master, remain resolutely on the ground. His relationship with Blair was one of equals and he never hesitates to answer back ("TB was starting to whinge and whine. I said I was fed up with him complaining and might he take the time today to thank some of the people who had worked flat out for the last few days to make it go as well as it had").

Light moments are few and far between, but there are some. The regular outings to see Campbell's beloved football team, Burnley, play  almost always ending in defeat. The occasion when he bravely intervenes to rescue a man being assaulted by four thugs  only to be denounced for his politics by the victim, who turns out to be a particularly sanctimonious Liberal Democrat. And in the middle of it all, baby Leo is born, thereby providing a few well-earned days of favourable press coverage  though even that has to be carefully stage-managed.

Campbell supplies yet more chapter and verse on the increasingly dysfunctional relationship between Blair and Brown, the fault line that ran through the New Labour project from start to finish. "Some of the stuff about Gordon is so bad that I don't think I can even put it in the unexpurgated version," Campbell remarked to me some years back. But it's all here. Gradually the scales fall from Blair's eyes. By December 1999 he is said "to fear that GB was actively working to undermine his government".

By February 2000, Blair is asking whether Gordon is up to being prime minister. It is frequently noted that Brown has a habit of going awol at key moments  the tanker drivers' strike, the foot and mouth epidemic. As late as April 2001 he is still denouncing Blair for having the temerity to run against him for the leadership seven years earlier ("you betrayed me. You said you would never challenge me"). Within days of Labour's second landslide victory, Brown is demanding that Blair name a date for stepping down. The wonder is that Blair put up with this nonsense for so long, but what choice did he have? On the backbenches Brown would have been a much bigger problem.

By the end one is left exhausted. What a joyless business modern government has become. The constant tabloid feeding frenzies. The dysfunctional relationships. Campbell's is the job from hell. He is worn down by it all ("the pressure is doing my head in"). Never off duty, rarely enjoying a decent night's sleep. To cap it all, his partner Fiona Millar (who herself works in No 10) is constantly pressing him to give up. Much of the misery is self-inflicted, of course  control freakery, hyperactivity, attempts to manipulate which frequently backfire. On the other hand, one can't help admiring Blair and Campbell for their extraordinary resilience, somehow managing to keep their eyes on the big picture while all around them mayhem reigns.

The worst, however, is yet to come. This volume ends on 11 September 2001, as the smoke billowed from the twin towers in New York. The wars in Iraq and Afghanistan and all that flowed from them are but a twinkle in the eye of George W Bush. For that we must await Campbell's fourth and final volume, due in the new year.

The third volume of Chris Mullin's diaries, A Walk on Part, will be published in August.

John Colville, Winston Churchill's private secretary, went riding at the height of the second world war; his boss went off to the cinema. Harold Macmillan, when prime minister, decamped to Scotland for weeks each August to go grouse shooting. The only communication was a single landline, and the occasional private secretary travelling on the overnight train with a red box of official papers. The foreign secretary's private office used simply to shut up shop for a week in August. A "Closed" notice was hung on the door. All callers were referred to the "resident clerks".

The central issue raised by this, the third volume of Alastair Campbell's diaries, Power and Responsibility, is how any British government can operate effectively in the now merciless, never-resting media cycle. In a self-critical passage in his introduction, Campbell writes: "Media pressures are all to be tactical, to respond to the agenda of others. That should force policy-makers to be more strategic. I'm not sure we always did that . . . Getting the balance right between the urgent and the important is not easy."

Campbell certainly had the intellectual capacity and the imagination to handle both the tactical and the strategic. At his best  which was most of the time  he was brilliant. Nor was he ever the sinister, Svengali-like manipulator that too many in the press sought to portray him as. As home secretary during most of the period covered by these diaries (May 1999, the Kosovo war, to 11 September 2001), in the thick of many of the touchstone issues of the day, I could be driven to distraction by Campbell  and, as his diaries record, he by me.

But I engaged with him, as most sensible members of Tony Blair's cabinet did, because he was always (and remains) for the party, of the party, because he had Blair's ear, but above all because he was always worth listening to. He had a more acute sense of how the British media operated than anyone I have ever met.

Campbell, like Blair, was constantly preoccupied with the knowledge that Labour had been elected with a proper majority just twice before in its history  in 1945 and 1966  and on both occasions had gone down to defeat at the following election through the absence of a sustaining strategy and an ability to manage the media.

Campbell had a Manichaean single-mindedness and the most extraordinary energy. After working similar hours to him, I would read a book and go to sleep. Campbell, who was ever accompanied by a thick A4 daybook in which he constantly scribbled his contemporaneous record of the day's events, would then write up his diaries at length, fail to sleep properly, and then rise early to deal with the next day's events.

Campbell's problems with the media, which intensified during the period covered by these diaries, were a product of the very qualities that made him so indispensable. He was everywhere. The reporters who dealt with him became as obsessed with him as he was with their product. He became the story. As the Conservatives under William Hague, and their allies in the press, became increasingly frustrated by their inability to do any lasting damage to Blair and his first-term government, they turned on Campbell. Thus "spin" became a metaphor for everything the dispossessed Conservatives really disliked about us  that we were in power, they were not, and had no serious possibility of regaining it for some years.

Until I read these diaries, I had forgotten how many difficulties there were that a better-led Conservative party  one led from the centre, not the right  could have exploited. Central to these was the interminable struggle, the unresolved conflict between the two founders of New Labour, Blair and Gordon Brown. This was not just about personality and power. As Campbell records in great detail, there were some profoundly important policy issues too, above all whether the UK should join the euro. From today's perspective it seems quaint that anyone could seriously have considered that it would have been in Britain's interests to join the single currency. With the benefit of hindsight, it would have been a disaster. Even had our entry been endorsed in a referendum, its adverse effects would have hobbled the party that recommended it for a generation. A dozen years ago, however, the perspective was very different. Thus the argument between the enthusiast Blair and the sceptic Brown ground on, wasting time and energy on a project which I thought could never fly.

This is a serious work, lightened occasionally by hilarious episodes. Campbell records bumping into the Conservative MP Nicholas Soames, "raging about hunting. 'How would you feel if we got back into power and passed a law banning Burnley fucking Football Club?'" I wish I'd thought of that.

Churchill and Macmillan could enjoy a little more leisure than any PM today because departmental ministers were, in the main, left to get on with their jobs. Even in the mid-70s Harold Wilson could parry a difficult question about an aspect of, say, Home Office policy with "I refer the honourable member to the secretary of state". Not now. An inevitable consequence of all-hours' media is that those in the centre  in Downing Street  are dragged into all manner of departmental stories. In any organisation there will be tension between those in the headquarters and those down the line. But the tensions are compounded in government by the constant demands from the centre on those running individual departments for instantaneous answers to sometimes near-intractable problems.

Campbell's, and Blair's, frustrations with the Home Office, and me, come out in the diaries. The feeling was mutual. When Blair surprised us all by announcing, via a line written by Campbell, that drunken yobs would be marched off to cash machines to pay on-the-spot fines, Campbell records that this had all "been pretty last-minute because the Home Office had been so useless". We weren't. It was an unworkable wheeze. There are limits to how far it is possible to push water uphill with one's bare hands.

That frustration emerges, in spades, over the fuel crisis that erupted without warning in September 2000. "On the train north TB spoke to Jack and said that we had to get the oil moving out of the blockaded refineries", Campbell writes. I recall thinking how helpful it was to have had that injunction of the blindingly obvious. If only the word was the act. What did he and his boss think we were trying to do (and in the end succeeded in doing) as we worked round the clock to get the tankers moving, from a standing start with no contingency plans of any kind for handling a fuel crisis, and not even a readily accessible map of where the refineries were?

As the government entered the run-up to the 2001 election, the pressures, even on a man with such an appetite for work, began to tell. Campbell records in poignant, sometimes toe-curling detail, the huge toll that his job was taking on his personal relationships. No man, however good, could survive such burdens. So, for what turned out to be just three months after the June 2001 election, Campbell did draw in his horns. But 9/11  the final day of this volume  changed everything.

The big question, which Campbell asks but does not answer in his introduction, is whether it will ever be possible to secure a better balance between the tactical and the strategic in an age of instant communications. It will be difficult to achieve, but Campbell's latest volume is instructive as both an example to follow and a sign of the pitfalls to avoid.

Colville's magisterial diaries, published as The Fringes of Power, cover 16 years, from 1939-55, but are 20 pages shorter than Campbell's, which cover just two and a half years. This latest volume is an important historical record, but my comradely advice to him and his editor is to cut the paperback version by half. The current volume is a good read, but requires too much dedication.

Jack Straw MP was home secretary 1997-2001.