Marines, of course, are trained to take the hill. Then there’s a group of leathernecks who actually have taken that mission to a different level, as in Capitol Hill. The lists of senators and representatives include Marines who served on active duty or in the reserves, and some saw combat. They bring a familiarity with the military, and the Marine Corps in particular, to a Congress whose members with military service represent less than 20 percent of both houses. In fact, the number of veterans serving in the House or Senate has hit its lowest since World War II. But veterans continue…