Complex sentence: Having recently attained Independence from Spain in 1821, Mexico was fraught with internal struggles that verged on civil war, however, in 1836 it was relatively united in refusing to recognize the independence of Texas.
Split into simpler sentences: Having recently attained independence from Spain in 1821, Mexico was fraught with internal struggles that verged on civil war. However, in 1836 it was relatively united in refusing to recognize the independence of Texas.