When U.S. and Mexican soldiers fought May 8, 1846, on the prairie land of Palo Alto at the southern tip of Texas, it was the match that ignited a two-year war between the two countries.The battlefield itself faded into American history, but not the legends. In June 1992, a law was passed creating Palo Alto Battlefield National Historical Park, preserving the 3,400-acre scene of the fighting, ten miles north of the Rio Grande River in what is now Cameron County."The battlefield itself is relatively intact, but the site has been gone over ever since the battle," Rolando Garza, archeologist and chief of resource management at Palo Alto Battlefield National Historical Park, told. "People would go out there and look for relics. We had one farmer tell us that he used to toss cannonballs into the (ravine) because he would hit them and they would damage his plow blade."Palo Alto Battlefield National Historical Park has the unique distinction of being the only unit of the National Park Service with a primary focus on the U.S.-Mexican War. With the creation of the park, all the relic hunting stopped, and in its place the park service has started an archeological survey of portions of the core battlefield area.Garza and his team developed a plan to create a grid of the battlefield, and between Feb. 20 and March 3, 2010 National Park Service archeologists from the Southeast Archeological Center (SEAC), NPS VIP archeologists, and 30 volunteers wielding metal detectors joined company to conduct this year's survey. It was the first of a three-year effort.Working on a shoestring budget, Garza was able to get funding for the survey work from the through the NPS cultural resources preservation program.Because Palo Alto Battlefield is a relatively new park-"We opened the visitor center in 2004," Garza said-a lot of effort is being made to develop trails for the public to follow which will tell the story of the fighting.Volunteer metal detector experts from as far away as Georgia and Florida joined local volunteers with experience in Mexican war sites to systematically cover approximately 100 acres of the battlefield in an effort to define battle lines, troop movements and reconcile the physical evidence with historic accounts.All items were mapped by GPS and carefully bagged for later stabilization and preservation. More than 1,100 volunteer hours were contributed to the project, and close to 700 battle-related artifacts were recovered."One of the things we've been searching for is the site of the Mexican Army's first flanking maneuver," Garza said. "We found some evidence, but it's not overwhelming. We do feel we are getting closer, however. This year, among other artifacts, we found a US Army breastplate. Its small, round and has an eagle on it."When the Mexican cavalry tried to do a flanking maneuver against the U.S. troops, they had a four-pound cannon with them. "We found a cannonball," he said.On May 8, 2010, the park will observe the 164th anniversary of the battle, and will have a variety of living history and ranger programs to mark the occasion.Additionally, on the first Saturday of each month, the park presents a living history program which includes demonstrations of weapons, tactics, and soldiers from the U.S.-Mexican War era, along with demonstrations of musket and artillery firing.Palo Alto Battlefield National Historical Park is located at the northeast corner of the intersection of FM 1847 ( Paredes Line Road) and FM 511, approximately five miles north of downtown Brownsville, Texas.Visit the Web site at