Its rich land and climate suitable for cotton drew the Americans toward it, and eventually the annexation of the Lone Star Republic--as it once was called--in 1845 seized the area from Mexico. As Mexico saw Texas as rightfully their land, the country began to attack the area and threatened to start a war. Yet, the United States government made matters worse by proclaiming the boundary of Texas to be the Rio Grande River while Mexico pushed for the border to be the Nueces River. Both powers were ready to fight for “their” territory, as stated in Document B where President James K. Polk assures Senator William H. Haywood that “[they] will not be the aggressor upon Mexico;...but if her army shall cross the Rio Grande del Norte and invade Texas, [they] will if [they] can drive her army to her own