The United States' armed conflict with Mexico largely emerged from Americans' eagerness to expand their nation westward to the Pacific Ocean. As American trappers and settlers poured across the Great Plains, many began to resent the fact that lands to the south and west of the Louisiana Purchase tract remained territories of Mexico, which had freed itself from Spanish colonial control in Americans' persistent attempts to settle these lands led to conflict with the Mexican government and, eventually, war. The Mexican Republic had welcomed Americans to settle in their northern territory of Texas in the s, but after a decade it became plain that the Americans disliked Mexican rule. In the American settlers revolted against Mexico and, in the following year, established their own Republic of Texas. Many Americans immediately began to demand that their nation make Texas a part of the United States.