I’ve attended most of the major antiwar protests in Washington since 9/11. At a 2005 protest, a cop tried to whack me on the head with a wooden pole. At a 2007 protest, I snapped a picture showing George W. Bush hanging next to the U.S. Capitol. But my favorite protest was a potent little ruckus that I almost missed. On a sunny late summer day in 2013, I ambled to downtown Washington to hike with a bunch of folks who enjoyed bantering as much as I did. The route for the jaunt started on the National Mall, passing by the Smithsonian, heading toward the World War II Memorial and points...