With its vast size and long frontier period, Texas was the scene of more combat events between Native American warriors and Anglo soldiers and settlers than any other state or territory. The US Army, therefore, erected more military outposts in Texas, a tradition begun by Spanish soldados and their presidios. Settlers built blockhouses and even stockades, the most famous of which was Parker's Fort, the site of an infamous massacre in 1836. Successive north to south lines of Army forts attempted to screen westward-moving settlers from war parties, while border posts stretched along the Rio Grande from Fort Brown on the Gulf of Mexico to Fort Bliss at El Paso del Norte. Texas was the site of the first US Cavalry regiment employed against horseback warriors, as well as the experimental US Camel Corps. From Robert E. Lee to Albert Sidney Johnston to Ranald Mackenzie, the Army's finest officers served out of Texas forts, and 61 Medals of Honor were earned by soldiers campaigning in the Lone Star State.