The painter had some insight to render this expression, which suggests a lot of emotions at the same time. You can read more about the exhibition of soldiers' paintings here.
Tom Lea / National Constitution Center via Reuters
"That 2,000 Yard Stare" painted by Tom Lea, World War Two, 1944. The painting is among about 300 paintings by U.S. servicemen and women that will be unveiled to the public for the first time at Philadelphia's National Constitution Center in September. The paintings have been selected from about 15,000 collected by the U.S. Army since the 1840s. Most have never been on public display. "Art of the American Soldier" focuses on the duties, sacrifices, and everyday lives of troops, and covers every conflict from the World War One to Afghanistan.