"Are we downhearted? No! Then let your voices ring and altogether sing," goes the patriotic song from the first world war. "Not while Britannia rules the waves. Not likely! While we have Jack upon the sea and Tommy on the land, we need not fret."

Almost a century later, in a different war led by George Bush and Tony Blair, and now by Barack Obama and David Cameron in Afghanistan and Iraq, patriotism is still rife in Washington and London. But one thing has changed: even if Jack was still a soldier, Tommy is probably now a private contractor. And those joining in the chorus are neither soldiers nor taxpayers, but corporate executives in boardrooms in Virginia and Texas.

For every soldier deployed in the decade long global war on terror, one private contractor worked alongside. The cost of this – according to the final report of the Commission on Wartime Contracting issued Wednesday – has been $206bn paid out to private contractors in the global war on terror. Roughly one out of every five dollars went to one contractor – KBR of Houston, Texas, a former subsidiary of Halliburton, which took in five times more than the next biggest contractor, Agility of Kuwait.

Outright fraud consumed something like 5-9% of that $206bn total, according to the commission, while waste was estimated to be as high as 20% of the total. All told, between $31bn and $60bn may have been misused, the commission estimates.

"It is disgusting to think that nearly a third of the billions and billions we spent on contracting was wasted or used for fraud," said senator Claire McCaskill, who helped create the commission.

"We are well aware of some of the deficiencies over the years in how we have worked contracts," US Marine Corps Colonel David Lapan, a Pentagon spokesman, told reporters. "In many instances, it's a matter of saving lives, doing things more quickly because of the nature of conflict."

The commissioners disagree. "It would be easy to prevent if we put the resources to prevent it," said Christopher Shays, a former congressman from Connecticut, who headed up the commission together with Michael Thibault, the former deputy director of the Defence Contract Audit Agency.

Some of the examples of waste, fraud and abuse clearly have little to do with saving lives. For example, Bearing Point, a US consultant, was paid $92m to mentor the Central Bank of Afghanistan, starting in 2003. International Relief and Development Inc, a contractor in Arlington, Virginia, was asked to distribute hundreds of millions of dollars' worth of seed and fertiliser to Afghan farmers in 2009.

The Afghan bankers gave out millions of dollars in loans that were never paid back and likely stolen from under the noses of the mentors, according to investigators (pdf). Meanwhile, as they found (pdf), the farmers sold the US supplies across the border to farmers in Pakistan. Yet other examples seem to directly contradict the reason for the war itself: Afghan truckers delivering food to US soldiers paid out millions of dollars in protection money to insurgent groups like the Taliban for protection (pdf).

"Contractors in such a position of trust should know that their duty to warn the government of impending crises overrides most other considerations," write the authors of the 240-page report (titled "Transforming Wartime Contracting: Controlling Costs, Reducing Risks"). The commission makes 15 specific recommendations on how to fix this problem. Yet they seemed to have missed the obvious one – questioning why US contractors are working to police bankers and farmers in Afghanistan, or why the Taliban are helping feed US troops. The answer isn't hard to find: profit. On average, the US government spent between $185,700 and $231,600 per US citizen contractor employed in Afghanistan and Iraq, says the commission.

Ten years after the attacks of 11 September, it is not too hard to find out who is humming the bars from "Are we downhearted?" sung in the musical, "Oh! What a Lovely War!" – a satire written to parody the generals and politicians who ignored the human cost of war. Today, it is easy to fight a war if you can pay contractors well to do the dirty work on your behalf. And it is even easier to write the cheques and turn a blind eye to the waste, fraud and abuse, than to come up with realistic long-term solutions that would benefit the people of Afghanistan and Iraq.