After Mexico attained independence from Spain in the 1920s, it allowed its people to settle in Texas which was not a densely populated. It so happened that most of the people who migrated to Texas were American who did not want to be ruled by the Mexican government because the Mexican government wanted to control the Americans population who were to migrate into Texas. This highly triggered Texas was fighting for their independence from Mexico which did not succeed until the mid-1830s when Texas declared its independence from Mexico and elected their 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 with Texas but Mexico was against the annexation threating 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 with the annexation with Texas was because of the strategically 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 state and the non-slave states.
After the opposition of the annex by Germany and France the United States changed its reasons to annex with Texas and promised protection and economic development of Texas as 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.