Over one million marched in London and millions elsewhere. Even the craven and weak Labour MPs split and over 120 voted against the war in parliament. Without the payroll vote of the Labour ministers and the Conservatives, Tony Blair would have been pushed close to defeat on his policy of backing the cowboy adventurism of the Bush administration.

Is it the beginning of the end of the American empire? In some ways you’d have to say no. After all, American imperialism has never seemed stronger. Its military might is greater than the rest of the world’s put together. The great enemy of Stalinist Russia and its acolytes has been vanquished – not by American might, but by the popular struggle of the masses. But it has seemingly left the US without any opposition (strikingly similar to lack of opposition, so far, to the New Labour administration of Blair). And the economic power of the US, apparently weakened during the post-war years as Japan and Germany became major industrial powers, appeared to be renewed during the great ‘hi-tech revolution’ of the 1990s in which the US was the leader and driver.

The 19th century was the century of British imperialism at its apex and it subsequent decline. The 20th century was the century of America’s rise to supremacy, first economically, then militarily in the Pacific against Japanese imperialism and finally as leader of the ‘free world’ against Stalinism.

But already at the end of that century, America was showing signs that its feet were not eagle’s claws but were made of clay. The great New Economy has turned out to be a myth. US productivity growth in the 1990s has been no faster than it was in the 1980s, and has been less than it was in the golden era of 1950-1973. The same was true for economic growth. The 1990s showed weakish growth by post-World War 2 standards.

Two things happened at the beginning of the new century and new millennium that suggest the next hundred years will not be ruled by Pax Americana. First, the great symbol and lubricant of capitalism, the US stock market, collapsed. For nearly three years with hardly a break, the stock markets of the world have fallen by up to 60%. The wealth of companies and rich households across the US empire has been wiped out. Big organisations have gone bankrupt or been found out cheating on their accounts to cover up their losses. In the US, the average household has lost nearly 25 of its paper wealth in stocks and shares. Of course, most Americans and Brits don’t have their wealth, such as it is, in the stock market. It is mostly in the value of their houses. And, so far, those values have held up handsomely. But even here, the death knell is beginning to ring.

Second, the banner of US economic might, the dollar, has begun to decline. In the last year alone, its value against Europe’s single currency fell by 15%. It has even weakened against the Japanese yen, a currency that is the economic flag of an economy that has been stagnating for nearly 14 years! Of the major currencies, only sterling has weakened along with the dollar. Just as Blair has tied the political interest of the British ruling class with the policies of Bush, so has sterling been caught in the same economic web that the old imperialist power of Britain is in with the new imperialism of the US.

Behind the bursting of the American stock market and currency bubbles lies the growing cancer within the economic body of the American empire. The Roman empire lasted for hundreds of years. No army could defeat it for long. There were temporary victories, one of the most long-lasting being the slave army revolt of Spartacus. But even he was eventually defeated militarily. What brought Rome to its knees was the eventual decline and failure of its economy. The Roman republic was an economy based on free peasants working the land. The empire led to the development of huge landed estates owned by the rich few. They needed masses to work the land. That meant slaves. Roman military conquest provided the manpower. But a slave economy eventually exhausts itself on declining productivity and manpower. It abhors technology (why bother when a slave can do it) and slaves don’t reproduce well or work well, on the whole. Eventually, the empire’s slave economy could no longer finance the extravagant consumption of the Caesars, the idle city population of free Romans and the military campaigns of bickering and feuding generals. It took a long time, but eventually Rome fell apart from within, drifting into Christian division and mythology.

The US has the same seeds of collapse within it. The stock market bubble was pricked because investors came to realise that the company shares they were buying at ever increasing prices would not deliver the profits that the companies claimed they would. US corporate profitability began to fall as early as 1997 but the light bulb only went on for investors in early 2000. Profitability died because, despite the New Economy, US multinationals could not get enough surplus value out of their workforce to compensate for the huge investment in the new technology they had made. They ‘over-invested’. Such is the Achilles heel of capitalism – production for people’s needs is subordinated to the realisation of private profit. Without profit, there will be no production. But profit cannot be created indefinitely and sufficiently to maintain investment because it arises by squeezing it out of the labour of others. There is no planning, but anarchy. There is no cooperation for maximum efficiency, but competition. The result is that boom is followed by slump.

It is no accident that just as the US economy begins to show its weakness, its emperors try to flex their muscles militarily. They must exert their military might to re-establish economic and political control both over the world’s resources (oil) and convince a confused people who might begin to question the very nature of the Empire. A war against Iraq takes the minds of people away from the whether “it is the economy, stupid” that’s the problem and turns it onto the idea of an evil Hitler of the Middle East who must be confronted and defeated. This Hitler was fostered and supported by the very Empire that now condemns him. Nothing was done to stop him gassing his own people or thousands of Iranians. All that is quietly forgotten. He only became Hitler when he misjudged the situation and tried to take over in Kuwait from an equally undemocratic bunch of gangsters. The Empire preferred the Sheikdom of Kuwait to Saddam to look after its oil, so he had to go.

And after 9/11, Saddam became more than Hitler. He was suddenly a friend of Al Qaeda, along with others in the Axis of Evil. And here is the beginning of the Empire’s decline (if not yet fall). Emperor Bush and his Senate seem set on taking on every ‘barbarian’ who does not kowtow to their will. Through an ‘alliance of the willing’, they are set to take on North Korea after Iraq and then perhaps Iran and Syria and even Libya and Cuba. Apparently Burma has been left off the list despite the nightmare dictatorship there; or China, where millions have been killed or displaced by the dictatorship there. But these ‘barbarians’ do not threaten the interests of the Empire, so they are not in the axis.

But is not this plan of permanent war going to be too much for the Empire’s economy to handle? The cost of the war against Iraq is estimated by the optimists to be just $50bn. That assumes a quick victory within weeks and maybe just two months of occupation by American troops before a new government friendly to the West is installed. A more pessimistic view might be that the war lasts several months and the occupation forces have to stay at least two years (it will be getting that way in Afghanistan). And then there is the cost of reconstructing a devastated economy – essential if a friendly government is to survive. That would cost closer to $150bn – large but manageable.

The real problem is this. If the war drags out and so does the occupation, oil prices could stay up very high (they are close to $40/b now). That will dramatically increase costs back in the Empire and its acolytes in the West. Spending will fall back and the world economy could slip into recession. The cost of this loss of output has been put at $1.5trn! That’s equivalent to knocking off 1% point from annual global GDP growth over the next five years.

Already the globe is not growing very fast. The Empire’s own economy was flat at the end of 2002. The UK economy grew at just above 1%. The German and Japanese economies did not move. If another 1% is knocked off growth each year over the next few years, recession and stagnation cannot be avoided. And that’s before the Empire moves on to the next confrontation with nuclear-armed North Korea or elsewhere.

The Empire looks as though it might be overstretching itself just when it seems that it is all-powerful. The economic failure of the Roman empire brought political division and collapse. That could happen to the American empire in this early part of the 21st century, just as the British empire folded in the early 20th century. The difference with the slave Roman empire is that there is a force in the world capable of replacing the American capitalist Empire with a new organisation for change – the working class. America’s decline and eventual fall does not mean anarchy and barbarism if that class succeeds.