In a scene that would have given Donald Trump heart palpitations, 200 flag-waving Mexican troops breached the U.S. border outside Laredo, Tex., 10 years ago and advanced unopposed up Interstate 35 to San Antonio. the Mexican soldiers were on a relief mission to feed tens of thousands of homeless and hungry Americans displaced by Hurricane Katrina. Setting up camp at a former Air Force base outside San Antonio, they distributed potable water, medical supplies and 7,000 hot meals a day for the next three weeks.