Raid on San Ygnacio  The Raid on San Ygnacio refers to a battle fought on June 15, 1916 between the United States Army and Mexican raiders near the border town of San Ygnacio, Texas. Three different Mexican factions were known to have launched raids into Texas at the time but most of the evidence suggests that either Seditionists or Carrancistas were responsible for the incursion. Four American soldiers were killed during the battle, along with at least six of the raiders, and the resulting American punitive expedition further strained the already hostile relationship between the Mexican and United States governments. The Mexican Revolution created widespread unrest in the border areas of the United States and Mexico. By early 1915, a group of Mexican rebels, calling themselves Seditionists, drafted the Plan of San Diego with the intention of bringing the American border states under the control of President Venustiano Carranza. They then began attacking military outposts, small towns, and ranches in South Texas. The Seditionists were originally led by Luis de la Rosa but, in June 1916, he was arrested by Carrancista authorities, while traveling to Monterey, and put under house arrest. According to Joseph Allan Stout, author of "Border conflict: Villistas, Carrancistas, and the Punitive Expedition," De la Rosa's arrest, combined with the previous capture of other Seditionist leaders, effectively ended the campaign by early 1916. However, Stout says that the superintendent of the Mexican National Railway, Esteban Fierros, was suspected of organizing raids during the summer of 1916, in accordance with the plan, and even ""scheduled an invasion of the United States"" to take place on June 10. Sure enough, that same day American soldiers pursued a band of raiders to Matamoros and just five days later San Ygnacio was attacked. The rebels of Pancho Villa were also active in raiding along the Texas border but the territory they controlled at the time was mostly in Chihuahua, far to the northwest of San Ygnacio. Also, the raid occurred while General John J. Pershing was dispersing Villa's forces as part of the Mexican Expedition. Therefore, it is unlikely that the Villistas were responsible. Finally, there was the Mexican Army, also known as the Constitutionalistas or Carrancistas, which had already shown hostility towards the United States on several occasions and threatened to kill American soldiers. On April 12, 1916, the Carrancistas backed up their threats and attacked the 13th Cavalry at Parral and after the San Ygnacio Raid, on June 21, they attacked the 10th Cavalry in the Battle of Carrizal.