Answer:
Mexico allows American settlers into Texas.
Texas declares independence.
The U.S. annexes Texas.
The U.S. declares war on Mexico.
Step-by-step explanation:
During the 1820's Mexican government let the American settlers to enter the territory of Texas. Still, through time tensions started rising, which led to the proclamation of Independence of Texas in 1836. Of course, this was just a premise of what was about the happen. The United States annexed Texas in 1845, which led to the war with Mexico in 1846, which was finished by victory of the States.