After Mexico attained independence from Spain in the 1920s, it allowed its people to settle in Texas, which was not densely populated. It so happened that most of the people who migrated to Texas were Americans who did not want to be ruled by the Mexican government because the Mexican government wanted to control the American population who were to migrate into Texas. This highly triggered Texas was fighting for its independence from Mexico, which did not succeed until the mid-1830s, when Texas declared its independence from Mexico and elected its first president Sam Houston in 1836. Mexico still did not recognize the independence of Texas and still regarded Texas as its state.
The United State wanted to annex Texas, but Mexico was against the annexation threatening that if the annexation was done, it would declare a civil war with the United States. The reason why the United States was so much interested in the annexation of Texas was because of the strategic position of Texas, which would support the westward expansion of the United States. The annex would only mean that Texas would be a slave state to the United State and would bring an imbalance to the law of the union’s constitution with regard to the number of slave states and non-slave states.
After the opposition to the annex by Germany and France, the United States changed its reasons for annexing with Texas and promised protection and economic development of Texas as a state of the United State. Later in 1945, the annex was successful, and Texas became a state of the United States, although the British argued that Texas accepted the annex due to fear of being attacked by the United State.