In the lingo of Capitol Hill they’re known as “codels.” Members of Congress go on congressional delegations to war zones and foreign capitals to burnish their national-security credentials and try their hand at personal diplomacy. The public often hears about them when congressmen are caught on TV playing golf or sipping a Mai Tai poolside, their trip exposed as a taxpayer-funded boondoggle. But sometimes they serve an important purpose, allowing politicians to grasp the nuances of a complicated foreign-policy issue or giving members a respite from the poisonous partisan climate in Washington.

One such time was July 2008, when Sens. Barack Obama, Chuck Hagel, and Jack Reed traveled together to Afghanistan and Iraq. Perhaps not a great premise for a buddy movie, but it was an intense bonding experience nonetheless. They delved deeply into policy discussions—“wonkfests,” as one former aide called them; shared personal stories from their vastly different backgrounds; and ribbed each other to pass the time on cramped military planes. (Obama teased Hagel for traveling to the battle zone in polished penny loafers.)