Now, at first glance it makes our Most Excellent Adventure in Iraq look like a bargain... but it's lying with statistics, as so often happens.

The Iraq Occupation has gone on for about 2.5 years following the initial invasion. The first Gulf War was indeed quick and cheap, unless you include the cost of sanctions enforcement (and if you're including the costs of the current occupation, it's only fair). The Vietnam conflict went on for over a decade, so on a per-year basis, it was a lot closer to the two more recent wars (thus demolishing the central claim of those citing the chart, which is that Iraq isn't like Vietnam). WWII was indeed a "total war" involving a massive committment of human and economic resources, but it lasted (for the US) four years (and I can't tell from these sources if the cost of occupying Germany and Japan are included), so it's not quite as dramatic as it looks. The Civil War, of course, is a special case, since the chart includes both sides: we were paying for the whole war not just one half of it, as usual.