Would Americans support foreign wars if they had to pay special, dedicated taxes to fund those wars? Here, A U.S. Air Force MQ-1B Predator drone sits at Incirlik Air Base in Turkey. (Courtesy of U.S. Air Force)

For many Americans, Tax Day means the drudgery of weeks, if not months, of preparing and filing paperwork. So it may be hard to believe that people originally clamored for income taxes. In the early 1860s, with the United States torn apart by the Civil War, Congress hesitated to adopt onerous war taxes. Its Revenue Act of 1861 adopted a modest income tax of up to 5 percent. But by 1862, the pitch for higher income taxes was resounding. Even the normally anti-tax Chicago Tribune urged the government to “levy the tax, and the war will go on!”

Congress levied additional revenue acts in 1862 and 1864. But in 1866, just a year after the war’s end, that same paper changed its tune. “We are, today, the most egregiously taxed people on the face of the earth. … The present income tax is nothing less than confiscation.” By 1872, the income tax was repealed.

Special war taxes keep the government accountable

American attitudes toward fiscal sacrifice in war have followed a similar arc as described for the Civil War. As John F. Kennedy put it, Americans have long been willing to “bear any burden, meet any hardship” to keep the nation safe — within limits, of course. Almost invariably, the United States has levied taxes to finance its wars. U.S. citizens have been willing to sacrifice — until the costs go up, the war’s aims become murky or the war goes on for too long.

That’s democratic accountability at work. When wars are worth the sacrifice, citizens are willing to pay. When wars are capricious or unreasonably costly, citizens pressure leaders to keep wars short and low cost.

So what happens when a war’s costs aren’t clear?

The accountability link between the government and the people has eroded in recent wars.  Rather than financing wars through special taxes, making the financial burden known to citizens, the federal government has borrowed instead. President George W. Bush even cut taxes after the 9/11 attacks, as the nation was ramping up both its domestic security apparatus and military operations in Afghanistan. The only effort to introduce a “share the sacrifice” war tax — in 2007, for the Iraq occupation, and in 2009, for Afghanistan — was led by antiwar members of Congress seeking to draw attention to the cost of those wars.

Does shielding the public from the costs of war actually affect attitudes about the war? Here’s what we found in our research, published at the Journal of Conflict Resolution.

To evaluate whether individuals’ support for war hinges on how they come into contact with the costs, we carried out a survey experiment through YouGov, an online polling firm. We surveyed 2,500 U.S. and 2,122 U.K. respondents, since both nations have, in recent decades, financed major conflicts through debt instead of war taxes.

After random assignment to control and treatment groups, respondents were presented a hypothetical war scenario and asked about their support for the war. Depending on the group, some respondents were told that the war would be financed in part through debt and others through war taxes. We also varied the type of mission — whether clear national interests, humanitarian intervention or a hybrid of the two.

Support for war goes down if taxpayers have to subtract the cost from their wallets by paying special taxes

We found that support for war is contingent on how the conflict is financed. When directly confronted with the burden of war in the form of taxes, support for war among Americans declined on average by 10 percentage points. For Britons, the decline was 12 points. And the decline in support took place no matter which party our respondent belonged to or what type of war we were discussing.

In other words, citizens are more willing to support their government’s military interventions if the government pays for them by borrowing instead of taxing. No longer are citizens reminded of the financial burden of conflict.

To be sure, individuals may know and not like that their country has high levels of debt. But that debt is free-floating, keeping the war at a distance from the public. And their detachment from that burden leads to less opposition to war — and, potentially, longer and more frequent wars.

As the sponsors of the 2009 bill to levy war-tax legislation variously said, “It’s important for people to understand how these wars are adding to our deficits. … We’re not trying to insult anybody. We’re just trying to keep in the forefront what the financial costs” of war are.

Gustavo Flores-Macias is an assistant professor of government at Cornell University and author of “After Neoliberalism? The Left and Economic Reforms in Latin America” (Oxford University Press 2012). Follow him on Twitter: @Gustavo_F_M.

Sarah Kreps is an associate professor of government at Cornell University and author of, most recently, “Drones: What Everyone Needs to Know” (Oxford University Press, 2016). Follow her on Twitter: @sekreps.